Apparatus and method for measuring optical characteristics of teeth

ABSTRACT

Optical characteristic measuring systems and methods such as for determining the color or other optical characteristics of teeth are disclosed. Perimeter receiver fiber optics are apart from a source fiber optic and receive light from the surface of the object/tooth being measured. Light from the perimeter fiber optics pass to a variety of filters. The system utilizes the perimeter receiver fiber optics to determine information regarding the height and angle of the probe with respect to the object/tooth being measured. Under processor control, the optical characteristics measurement may be made at a predetermined height and angle. Various color spectral photometer arrangements are disclosed. Translucency, fluorescence, gloss and/or surface texture data also may be obtained. Audio feedback may be provided to guide operator use of the system. The probe may have a removable or shielded tip for contamination prevention. A method of producing dental prostheses based on measured data also is disclosed. Measured data also may be stored and/or organized as part of a patient data base.

FIELD OF THE INVENTION

[0001] The present invention relates to devices and methods formeasuring optical characteristics such as color spectrums, translucence,gloss, and other characteristics of objects such as teeth, and moreparticularly to devices and methods for measuring the color and otheroptical characteristics of teeth or other objects or surfaces with ahand-held probe that presents minimal problems with height or angulardependencies.

BACKGROUND OF THE INVENTION

[0002] A need has been recognized for devices and methods of measuringthe color or other optical characteristics of teeth and other objects inthe field of dentistry. Various color measuring devices such asspectrophotometers and colorimeters are known in the art. To understandthe limitations of such conventional devices, it is helpful tounderstand certain principles relating to color. Without being bound bytheory, Applicants provide the following discussion. In the discussionherein, reference is made to an “object,” “material,” “surface,” etc.,and it should be understood that in general such discussion may includeteeth as the “object,” “material,” “surface,” etc.

[0003] The color of an object determines the manner in which light isreflected from the object. When light is incident upon an object, thereflected light will vary in intensity and wavelength dependent upon thecolor of the object. Thus, a red object will reflect red light with agreater intensity than a blue or a green object, and correspondingly agreen object will reflect green light with a greater intensity than ared or blue object.

[0004] The optical properties of an object are also affected by themanner in which light is reflected from the surface. Glossy objects,those that reflect light specularly such as mirrors or other highlypolished surfaces, reflect light differently than diffuse objects orthose that reflect light in all directions, such as the reflection froma rough or otherwise non-polished surface. Although both objects mayhave the same color and exhibit the same reflectance or absorptionoptical spectral responses, their appearances differ because of themanner in which they reflect light.

[0005] Additionally, many objects may be translucent or havesemi-translucent surfaces or thin layers covering their surfaces.Examples of such materials are teeth, which have a complicated structureconsisting of an outer enamel layer and an inner dentin layer. The outerenamel layer is semitranslucent. The inner layers are also translucentto a greater or lesser degree. Such materials and objects also appeardifferent from objects that are opaque, even though they may be the samecolor because of the manner in which they can propagate light in thetranslucent layer and emit the light ray displaced from its point ofentry.

[0006] One method of quantifying the color of an object is to illuminateit with broad band spectrum or “white” light, and measure the spectralproperties of the reflected light over the entire visible spectrum andcompare the reflected spectrum with the incident light spectrum. Suchinstruments typically require a broad band spectrophotometer, whichgenerally are expensive, bulky and relatively cumbersome to operate,thereby limiting the practical application of such instruments.

[0007] For certain applications, the broad band data provided by aspectrophotometer is unnecessary. For such applications, devices havebeen produced or proposed that quantify color in terms of a numericalvalue or relatively small set of values representative of the color ofthe object.

[0008] It is known that the color of an object can be represented bythree values. For example, the color of an object can be represented byred, green and blue values, an intensity value and color differencevalues, by a CIE value, or by what are known as “tristimulus values” ornumerous other orthogonal combinations. For most tristimulus systems,the three values are orthogonal; i.e., any combination of two elementsin the set cannot be included in the third element.

[0009] One such method of quantifying the color of an object is toilluminate an object with broad band “white” light and measure theintensity of the reflected light after it has been passed through narrowband filters. Typically three filters (such as red, green and blue) areused to provide tristimulus light values representative of the color ofthe surface. Yet another method is to illuminate an object with threemonochromatic light sources or narrow band light sources (such as red,green and blue) one at a time and then measure the intensity of thereflected light with a single light sensor. The three measurements arethen converted to a tristimulus value representative of the color of thesurface. Such color measurement techniques can be utilized to produceequivalent tristimulus values representative of the color of thesurface. Generally, it does not matter if a “white” light source is usedwith a plurality of color sensors (or a continuum in the case of aspectrophotometer), or if a plurality of colored light sources areutilized with a single light sensor.

[0010] There are, however, difficulties with the conventionaltechniques. When light is incident upon a surface and reflected to alight receiver, the height of the light sensor and the angle of thesensor relative to the surface and to the light source also affect theintensity of the received light. Since the color determination is beingmade by measuring and quantifying the intensity of the received lightfor different colors, it is important that the height and angulardependency of the light receiver be eliminated or accounted for in somemanner.

[0011] One method for eliminating the height and angular dependency ofthe light source and receiver is to provide a fixed mounting arrangementwhere the light source and receiver are stationary and the object isalways positioned and measured at a preset height and angle. The fixedmounting arrangement greatly limits the applicability of such a method.Another method is to add mounting feet to the light source and receiverprobe and to touch the object with the probe to maintain a constantheight and angle. The feet in such an apparatus must be wide enoughapart to insure that a constant angle (usually perpendicular) ismaintained relative to the object. Such an apparatus tends to be verydifficult to utilize on small objects or on objects that are hard toreach, and in general does not work satisfactorily in measuring objectswith curved surfaces. Such devices are particularly difficult toimplement in the field of dentistry.

[0012] The use of color measuring devices in the field of dentistry hasbeen proposed. In modern dentistry, the color of teeth typically arequantified by manually comparing a patient's teeth with a set of “shadeguides.” There are numerous shade guides available for dentists in orderto properly select the desired color of dental prosthesis. Such shadeguides have been utilized for decades and the color determination ismade subjectively by the dentist by holding a set of shade guides nextto a patient's teeth and attempting to find the best match.Unfortunately, however, the best match often is affected by the ambientlight color in the dental operatory and the surrounding color of thepatient's makeup or clothing and by the fatigue level of the dentist. Inaddition, such pseudo trial and error methods based on subjectivematching with existing industry shade guides for forming dentalprostheses, fillings and the like often result in unacceptable colormatching, with the result that the prosthesis needs to be remade,leading to increased costs and inconvenience to the patient, dentalprofessional and/or prosthesis manufacturer.

[0013] Similar subjective color quantification also is made in the paintindustry by comparing the color of an object with a paint referenceguide. There are numerous paint guides available in the industry and thecolor determination also often is affected by ambient light color, userfatigue and the color sensitivity of the user. Many individuals arecolor insensitive (color blind) to certain colors, further complicatingcolor determination.

[0014] While a need has been recognized in the field of dentistry,however, the limitations of conventional color/optical measuringtechniques typically restrict the utility of such techniques. Forexample, the high cost and bulkiness of typical broad bandspectrometers, and the fixed mounting arrangements or feet required toaddress the height and angular dependency, often limit the applicabilityof such conventional techniques.

[0015] Moreover, another limitation of such conventional methods anddevices are that the resolution of the height and angular dependencyproblems typically require contact with the object being measured. Incertain applications, it may be desirable to measure and quantify thecolor of an object with a small probe that does not require contact withthe surface of the object. In certain applications, for example,hygienic considerations make such contact undesirable. In the otherapplications, contact with the object can mar the surface (such as ifthe object is coated in some manner) or otherwise cause undesirableeffects.

[0016] In summary, there is a need for a low cost, hand-held probe ofsmall size that can reliably measure and quantify the color and otheroptical characteristics of an object without requiring physical contactwith the object, and also a need for methods based on such a device inthe field of dentistry and other applications.

SUMMARY OF THE INVENTION

[0017] In accordance with the present invention, devices and methods areprovided for measuring the color and other optical characteristics ofobjects such as teeth, reliably and with minimal problems of height andangular dependence. A handheld probe is utilized in the presentinvention, with the handheld probe containing a number of fiber opticsin certain preferred embodiments. Light is directed from one (or more)light source(s) towards the object/tooth to be measured, which incertain preferred embodiments is a central light source fiber optic(other light sources and light source arrangements also may beutilized). Light reflected from the object is detected by a number oflight receivers. Included in the light receivers (which may be lightreceiver fiber optics) are a plurality of perimeter and/or broadband orother receivers (which may be light receiver fiber optics, etc.). Incertain preferred embodiments, a number of groups of perimeter fiberoptics are utilized in order to take measurements at a desired, andpredetermined height and angle, thereby minimizing height and angulardependency problems found in conventional methods, and to quantify otheroptical characteristics such as gloss. In certain embodiments, thepresent invention also may measure gloss, translucence and fluorescencecharacteristics of the object/tooth being measured, as well as surfacetexture and/or other optical or surface characteristics. In certainembodiments, the present invention may distinguish the surface spectralreflectance response and also a bulk spectral response.

[0018] The present invention may include constituent elements of a broadband spectrophotometer, or, alternatively, may include constituentelements of a tristimulus type colorimeter. The present invention mayemploy a variety of color measuring devices in order to measure colorand other optical characteristics in a practical, reliable and efficientmanner, and in certain preferred embodiments includes a color filterarray and a plurality of color sensors. A microprocessor is included forcontrol and calculation purposes. A temperature sensor is included tomeasure temperature in order to detect abnormal conditions and/or tocompensate for temperature effects of the filters or other components ofthe system. In addition, the present invention may include audiofeedback to guide the operator in making color/optical measurements, aswell as one or more display devices for displaying control, status orother information.

[0019] With the present invention, color/optical measurements of teethor the like may be made with a handheld probe in a practical andreliable manner, essentially free of height and angular dependencyproblems, without resorting to fixtures, feet or other undesirablemechanical arrangements for fixing the height and angle of the probewith respect to the object/tooth. In addition, the present inventionincludes methods of using such color measurement data to implementprocesses for forming dental prostheses and the like, as well as methodsfor keeping such color and/or other data as part of a patient recorddatabase.

[0020] Accordingly, it is an object of the present invention to addresslimitations of conventional color/optical measuring techniques.

[0021] It is another object of the present invention to provide a methodand device useful in measuring the color or other opticalcharacteristics of teeth or other objects or surfaces with a hand-heldprobe of practical size that may advantageously utilize, but does notnecessarily require, contact with the object or surface.

[0022] It is a further object of the present invention to provide acolor/optical measurement probe and method that does not require, fixedposition mechanical mounting, feet or other mechanical impediments.

[0023] It is yet another object of the present invention to provide aprobe and method useful for measuring color and/or other opticalcharacteristics that may be utilized with a probe simply placed near thesurface to be measured.

[0024] It is a still further object of the present invention to providea probe and method that are capable of determining translucencycharacteristics of the object being measured.

[0025] It is a still further object of the present invention to providea probe and method that are capable of determining translucencycharacteristics of the object being measured by making measurements fromone side of the object.

[0026] It is a further object of the present invention to provide aprobe and method that are capable of determining surface texturecharacteristics of the object/tooth being measured.

[0027] It is a still further object of the present invention to providea probe and method that are capable of determining fluorescencecharacteristics of the object/tooth being measured.

[0028] It is yet a further object of the present invention to provide aprobe and method that are capable of determining gloss (or degree ofspecular reflectance) characteristics of the object/tooth beingmeasured.

[0029] It is another object of the present invention to provide a probeand method that can measure the area of a small spot singularly, or thatalso can measure the color of irregular shapes by moving the probe overan area and integrating the color of the entire area.

[0030] It is a further object of the present invention to provide amethod of measuring the color of teeth and preparing dental prostheses,dentures, intraoral tooth-colored fillings or other materials.

[0031] It is yet another object of the present invention to provide amethod and apparatus that minimizes contamination problems, whileproviding a reliable and expedient manner in which to measure teeth andprepare dental prostheses, dentures, intraoral tooth-colored fillings orother materials.

[0032] It is an object of the present invention to provide methods ofusing measured data to implement processes for forming dental prosthesesand the like, as well as methods for keeping such measurement and/orother data as part of a patient record database.

[0033] It also is an object of the present invention to provide probesand methods for measuring optical characteristics with a probe that isheld substantially stationary with respect to the object or tooth beingmeasured.

[0034] Finally, it is an object of the present invention to provideprobes and methods for measuring optical characteristics with a probethat may have a removable tip or shield that may be removed forcleaning, disposed after use or the like

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention may be more fully understood by adescription of certain preferred embodiments in conjunction with theattached drawings in which:

[0036]FIG. 1 is a diagram illustrating a preferred embodiment of thepresent invention;

[0037]FIG. 2 is a diagram illustrating a cross section of a probe thatmay be used in accordance with certain embodiments of the presentinvention;

[0038]FIG. 3 is a diagram illustrating an illustrative arrangement offiber optic receivers and sensors utilized with certain embodiments;

[0039]FIGS. 4A to 4C illustrate certain geometric considerations offiber optics;

[0040]FIGS. 5A and 5B illustrate the light amplitude received by fiberoptic light receivers as the receivers are moved towards and away froman object;

[0041]FIG. 6 is a flow chart illustrating a color measuring method inaccordance with an embodiment of the present invention;

[0042]FIGS. 7A and 7B illustrate a protective cap that may be used withcertain embodiments of the present invention;

[0043]FIGS. 8A and 8B illustrate removable probe tips that may be usedwith certain embodiments of the present invention;

[0044]FIG. 9 illustrates a fiber optic bundle in accordance with anotherembodiment, which may serve to further the understanding of preferredembodiments of the present invention;

[0045]FIGS. 10A, 10B, 10C and 10D illustrate and describe other fiberoptic bundle configurations and principles, which may serve to furtherthe understanding of preferred embodiments of the present invention;

[0046]FIG. 11 illustrates a linear optical sensor array that may be usedin certain embodiments of the present invention;

[0047]FIG. 12 illustrates a matrix optical sensor array that may be usedin certain embodiments of the present invention;

[0048]FIGS. 13A and 13B illustrate certain optical properties of afilter array that may be used in certain embodiments of the presentinvention;

[0049]FIGS. 14A and 14B illustrate examples of received lightintensities of receivers used in certain embodiments of the presentinvention;

[0050]FIG. 15 is a flow chart illustrating audio tones that may be usedin certain preferred embodiments of the present invention;

[0051]FIGS. 16A and 16B are flow charts illustrating dental prosthesismanufacturing methods in accordance with certain preferred embodimentsof the present invention;

[0052]FIGS. 17A and 17B illustrate a positioning implement used incertain embodiments of the present invention;

[0053]FIG. 18 is a flow chart illustrating a patient database method inaccordance with certain embodiments of the present invention;

[0054]FIG. 19 illustrates an integrated unit in accordance with thepresent invention that includes a measuring device and other implements;

[0055]FIG. 20 illustrates an embodiment, which utilizes a plurality ofrings of light receivers that may be utilized to take measurements withthe probe held substantially stationary with respect to the object beingmeasured, which may serve to further the understanding of preferredembodiments of the present invention;

[0056]FIGS. 21 and 22 illustrate an embodiment, which utilizes amechanical movement and also may be utilized to take measurements withthe probe held substantially stationary with respect to the object beingmeasured, which may serve to further the understanding of preferredembodiments of the present invention;

[0057]FIGS. 23A to 23C illustrate embodiments of the present inventionin which coherent light conduits may serve as removable probe tips;

[0058]FIGS. 24, 25 and 26 illustrate further embodiments of the presentinvention utilizing intraoral reflectometers, intraoral cameras and/orcolor calibration charts in accordance with the present invention;

[0059]FIG. 27 illustrates an embodiment of the present invention inwhich an interoral camera and/or other instruments in accordance withthe present invention may be adapted for use with a dental chair;

[0060]FIGS. 28A and 28B illustrate cross sections of probes that may beused in accordance with preferred embodiments of the present invention;

[0061]FIGS. 29 and 30A and 30B illustrate certain geometric and otherproperties of fiber optics for purposes of understanding certainpreferred embodiments;

[0062]FIGS. 31A and 31B illustrate probes for measuring“specular-excluded” type spectrums in accordance with the presentinvention;

[0063]FIGS. 32, 33 and 34 illustrate embodiments in which intra oralcameras and reflectometer type instruments in accordance with thepresent invention are integrated;

[0064]FIGS. 35 and 36 illustrate certain handheld embodiments of thepresent invention;

[0065]FIGS. 37A and 37B illustrate a tooth dental object in crosssection, illustrating how embodiments of the present invention may beused to assess subsurface characteristics of various types of objects;and

[0066] FIGS. 38 to 50 illustrate other embodiments (systems, sources,receivers, etc.), aspects and features within the scope of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] The present invention will be described in greater detail withreference to certain preferred embodiments and certain otherembodiments, which may serve to further the understanding of preferredembodiments of the present invention. At various places herein,reference is made to an “object,” “material,” “surface,” etc., forexample. It should be understood that an exemplary use of the presentinvention is in the field of dentistry, and thus the object typicallyshould be understood to include teeth, dentures or other prosthesis orrestorations, dental-type cements or the like or other dental objects,although for discussion purposes in certain instances reference is onlymade to the “object.” As described elsewhere herein, various refinementsand substitutions of the various embodiments are possible based on theprinciples and teachings herein.

[0068] With reference to FIG. 1, an exemplary preferred embodiment of acolor/optical characteristic measuring system and method in accordancewith the present invention will be described. It should be noted that,at various places herein, such a color measuring system is sometimesreferred to as an intraoral reflectometer, etc.

[0069] Probe tip 1 encloses a plurality of fiber optics, each of whichmay constitute one or more fiber optic fibers. In a preferredembodiment, the fiber optics contained within probe tip 1 includes asingle light source fiber optic and a number of groups of light receiverfiber optics. The use of such fiber optics to measure the color or otheroptical characteristics of an object will be described later herein.Probe tip 1 is attached to probe body 2, on which is fixed switch 17.Switch 17 communicates with microprocessor 10 through wire 18 andprovides, for example, a mechanism by which an operator may activate thedevice in order to make a color/optical measurement. Fiber optics withinprobe tip 1 terminate at the forward end thereof (i.e., the end awayfrom probe body 2). The forward end of probe tip 1 is directed towardsthe surface of the object to be measured as described more fully below.The fiber optics within probe tip 1 optically extend through probe body2 and through fiber optic cable 3 to light sensors 8, which are coupledto microprocessor 10.

[0070] It should be noted that microprocessor 10 includes conventionalassociated components, such as memory (programmable memory, such asPROM, EPROM or EEPROM; working memory such as DRAMs or SRAMs; and/orother types of memory such as non-volatile memory, such as FLASH),peripheral circuits, clocks and power supplies, although for claritysuch components are not explicitly shown. Other types of computingdevices (such as other microprocessor systems, programmable logic arraysor the like) are used in other embodiments of the present invention.

[0071] In the embodiment of FIG. 1, the fiber optics from fiber opticcable 3 end at splicing connector 4. From splicing connector 4, each orsome of the receiver fiber optics used in this embodiment is/are splicedinto a number of smaller fiber optics (generally denoted as fibers 7),which in this embodiment are fibers of equal diameter, but which inother preferred embodiments may be of unequal diameter and/or numericaperture (NA) (including, for example, larger or smaller “height/angle”or perimeter fibers, as more fully described herein). One of the fibersof each group of fibers may pass to light sensors 8 through a neutraldensity filter (as more fully described with reference to FIG. 3), andcollectively such neutrally filtered fibers may be utilized for purposesof height/angle determination, translucency determination and glossdetermination (and also may be utilized to measure other surfacecharacteristics, as more fully described herein). Remaining fibers ofeach group of fibers may pass to light sensors 8 through color filtersand may be used to make color/optical measurements. In still otherembodiments, splicing connector 4 is not used, and fiber bundles of, forexample, five or more fibers each extend from light sensors 8 to theforward end of probe tip 1. In certain embodiments, unused fibers orother materials may be included as part of a bundle of fibers forpurposes of, for example, easing the manufacturing process for the fiberbundle. What should be noted is that, for purposes of the presentinvention, a plurality of light receiver fiber optics or elements (suchas fibers 7) are presented to light sensors 8, with the light from thelight receiver fiber optics/elements representing light reflected fromobject 20. While the various embodiments described herein presenttradeoffs and benefits that may not have been apparent prior to thepresent invention (and thus may be independently novel), what isimportant for the present discussion is that light from fiberoptics/elements at the forward end of probe tip 1 is presented tosensors 8 for color/optical measurements and angle/height determination,etc. In particular, fiber optic configurations of certain preferredembodiments will be explained in more detail hereinafter.

[0072] Light source 11 in the preferred embodiment is a halogen lightsource (of, for example, 5-100 watts, with the particular wattage chosenfor the particular application), which may be under the control ofmicroprocessor 10. The light from light source 11 reflects from coldmirror 6 and into source fiber optic 5. Source fiber optic 5 passesthrough to the forward end of probe tip 1 and provides the lightstimulus used for purposes of making the measurements described herein.Cold mirror 6 reflects visible light and passes infra-red light, and isused to reduce the amount of infra-red light produced by light source 11before the light is introduced into source fiber optic 5. Such infra-redlight reduction of the light from a halogen source such as light source11 can help prevent saturation of the receiving light sensors, which canreduce overall system sensitivity. Fiber 15 receives light directly fromlight source 11 and passes through to light sensors 8 (which may bethrough a neutral density filter). Microprocessor 10 monitors the lightoutput of light source 11 through fiber 15, and thus may monitor and, ifnecessary compensate for, drift of the output of light source 11. Incertain embodiments, microprocessor 10 also may sound an alarm (such asthrough speaker 16) or otherwise provide some indication if abnormal orother undesired performance of light source 11 is detected.

[0073] The data output from light sensors 8 pass to microprocessor 10.Microprocessor 10 processes the data from light sensors 8 to produce ameasurement of color and/or other characteristics. Microprocessor 10also is coupled to key pad switches 12, which serve as an input device.Through key pad switches 12, the operator may input control informationor commands, or information relating to the object being measured or thelike. In general, key pad switches 12, or other suitable data inputdevices (such as push button, toggle, membrane or other switches or thelike), serve as a mechanism to input desired information tomicroprocessor 10.

[0074] Microprocessor 10 also communicates with UART 13, which enablesmicroprocessor 10 to be coupled to an external device such as computer13A. In such embodiments, data provided by microprocessor 10 may beprocessed as desired for the particular application, such as foraveraging, format conversion or for various display or print options,etc. In the preferred embodiment, UART 13 is configured so as to providewhat is known as a RS232 interface, such as is commonly found inpersonal computers.

[0075] Microprocessor 10 also communicates with LCD 14 for purposes ofdisplaying status, control or other information as desired for theparticular application. For example, color bars, charts or other graphicrepresentations of the color or other collected data and/or the measuredobject or tooth may be displayed. In other embodiments, other displaydevices are used, such as CRTs, matrix-type LEDs, lights or othermechanisms for producing a visible indicia of system status or the like.Upon system initialization, for example, LCD 14 may provide anindication that the system is stable, ready and available for takingcolor measurements.

[0076] Also coupled to microprocessor 10 is speaker 16. Speaker 16, in apreferred embodiment as discussed more fully below, serves to provideaudio feedback to the operator, which may serve to guide the operator inthe use of the device. Speaker 16 also may serve to provide status orother information alerting the operator of the condition of the system,including an audio tone, beeps or other audible indication (i.e., voice)that the system is initialized and available for taking measurements.Speaker 16 also may present audio information indicative of the measureddata, shade guide or reference values corresponding to the measureddata, or an indication of the status of the color/optical measurements.

[0077] Microprocessor 10 also receives an input from temperature sensor9. Given that many types of filters (and perhaps light sources or othercomponents) may operate reliably only in a given temperature range,temperature sensor 9 serves to provide temperature information tomicroprocessor 10. In particular, color filters, such as may be includedin light sensors 8, may be sensitive to temperature, and may operatereliably only over a certain temperature range. In certain embodiments,if the temperature is within a usable range, microprocessor 10 maycompensate for temperature variations of the color filters. In suchembodiments, the color filters are characterized as to filteringcharacteristics as a function of temperature, either by data provided bythe filter manufacturer, or through measurement as a function oftemperature. Such filter temperature compensation data may be stored inthe form of a look-up table in memory, or may be stored as a set ofpolynomial coefficients from which the temperature characteristics ofthe filters may be computed by microprocessor 10.

[0078] In general, under control of microprocessor 10, which may be inresponse to operator activation (through, for example, key pad switches12 or switch 17), light is directed from light source 11, and reflectedfrom cold mirror 6 through source fiber optic 5 (and through fiber opticcable 3, probe body 2 and probe tip 1) or through some other suitablelight source element and is directed onto object 20. Light reflectedfrom object 20 passes through the receiver fiber optics/elements inprobe tip 1 to light sensors 8 (through probe body 2, fiber optic cable3 and fibers 7). Based on the information produced by light sensors 8,microprocessor 10 produces a color/optical measurement result or otherinformation to the operator. Color measurement or other data produced bymicroprocessor 10 may be displayed on display 14, passed through UART 13to computer 13A, or used to generate audio information that is presentedto speaker 16. Other operational aspects of the preferred embodimentillustrated in FIG. 1 will be explained hereinafter.

[0079] With reference to FIG. 2, an embodiment of a fiber opticarrangement presented at the forward end of probe tip 1 will now bedescribed, which may serve to further the understanding of preferredembodiments of the present invention. As illustrated in FIG. 2, thisembodiment utilizes a single central light source fiber optic, denotedas light source fiber optic S, and a plurality of perimeter lightreceiver fiber optics, denoted as light receivers R1, R2 and R3. As isillustrated, this embodiment utilizes three perimeter fiber optics,although in other embodiments two, four or some other number of receiverfiber optics are utilized. As more fully described herein, the perimeterlight receiver fiber optics serve not only to provide reflected lightfor purposes of making the color/optical measurement, but such perimeterfibers also serve to provide information regarding the angle and heightof probe tip 1 with respect to the surface of the object that is beingmeasured, and also may provide information regarding the surfacecharacteristics of the object that is being measured.

[0080] In the illustrated embodiment, receiver fiber optics R1 to R3 arepositioned symmetrically around source fiber optic S, with a spacing ofabout 120 degrees from each other. It should be noted that spacing t isprovided between receiver fiber optics R1 to R3 and source fiber opticS. While the precise angular placement of the receiver fiber opticsaround the perimeter of the fiber bundle in general is not critical, ithas been determined that three receiver fiber optics positioned 120degrees apart generally may give acceptable results. As discussed above,in certain embodiments light receiver fiber optics R1 to R3 eachconstitute a single fiber, which is divided at splicing connector 4(refer again to FIG. 1), or, in alternate embodiments, light receiverfiber optics R1 to R3 each constitute a bundle of fibers, numbering, forexample, at least five fibers per bundle. It has been determined that,with available fibers of uniform size, a bundle of, for example, sevenfibers may be readily produced (although as will be apparent to one ofskill in the art, the precise number of fibers may be determined in viewof the desired number of receiver fiber optics, manufacturingconsiderations, etc.). The use of light receiver fiber optics R1 to R3to produce color/optical measurements is further described elsewhereherein, although it may be noted here that receiver fiber optics R1 toR3 may serve to detect whether, for example, the angle of probe tip 1with respect to the surface of the object being measured is at 90degrees, or if the surface of the object being measured contains surfacetexture and/or spectral irregularities. In the case where probe tip 1 isperpendicular to the surface of the object being measured and thesurface of the object being measured is a diffuse reflector (i.e., amatte-type reflector, as compared to a glossy or spectral or shiny-typereflector which may have “hot spots”), then the light intensity inputinto the perimeter fibers should be approximately equal. It also shouldbe noted that spacing t serves to adjust the optimal height at whichcolor/optical measurements should be made (as more fully describedbelow). Preferred embodiments, as described hereinafter, may enable thequantification of the gloss or degree of spectral reflection of theobject being measured.

[0081] In one particular aspect useful with embodiments of the presentinvention, area between the fiber optics on probe tip 1 may be wholly orpartially filled with a non-reflective material and/or surface; (whichmay be a black mat, contoured or other non-reflective surface). Havingsuch exposed area of probe tip 1 non-reflective helps to reduceundesired reflections, thereby helping to increase the accuracy andreliability.

[0082] With reference to FIG. 3, a partial arrangement of light receiverfiber optics and sensors that may be used in a preferred embodiment ofthe present invention will now be described. Fibers 7 represent lightreceiving fiber optics, which transmit light reflected from the objectbeing measured to light sensors 8. In an exemplary embodiment, sixteensensors (two sets of eight) are utilized, although for ease ofdiscussion only 8 are illustrated in FIG. 3 (in this preferredembodiment, the circuitry of FIG. 3 is duplicated, for example, in orderto result in sixteen sensors). In other embodiments, other numbers ofsensors are utilized in accordance with the present invention.

[0083] Light from fibers 7 is presented to sensors 8, which in apreferred embodiment pass through filters 22 to sensing elements 24. Inthis preferred embodiment, sensing elements 24 includelight-to-frequency converters, manufactured by Texas Instruments andsold under the part number TSL230. Such converters constitute, ingeneral, photo diode arrays that integrate the light received fromfibers 7 and output an AC signal with a frequency proportional to theintensity (not frequency) of the incident light. Without being bound bytheory, the basic principle of such devices is that, as the intensityincreases, the integrator output voltage rises more quickly, and theshorter the integrator rise time, the greater the output frequency. Theoutputs of the TSL230 sensors are TTL compatible digital signals, whichmay be coupled to various digital logic devices.

[0084] The outputs of sensing elements 24 are, in this embodiment,asynchronous signals of frequencies depending upon the light intensitypresented to the particular sensing elements, which are presented toprocessor 26. In a preferred embodiment, processor 26 is a MicrochipPIC16C55 or PIC16C57 microprocessor, which as described more fullyherein implements an algorithm to measure the frequencies of the signalsoutput by sensing elements 24. In other embodiments, a more integratedmicroprocessor/microcontroller, such as Hitachi's SH RISCmicrocontrollers, is utilized to provide further system integration orthe like.

[0085] As previously described, processor 26 measures the frequencies ofthe signals output from sensing elements 24. In a preferred embodiment,processor 26 implements a software timing loop, and at periodicintervals processor 26 reads the states of the outputs of sensingelements 24. An internal counter is incremented each pass through thesoftware timing loop. The accuracy of the timing loop generally isdetermined by the crystal oscillator time base (not shown in FIG. 3)coupled to processor 26 (such oscillators typically are quite stable).After reading the outputs of sensing elements 24, processor 26 performsan exclusive OR (“XOR”) operation with the last data read (in apreferred embodiment such data is read in byte length). If any bit haschanged, the XOR operation will produce a 1, and, if no bits havechanged, the XOR operation will produce a 0. If the result is non-zero,the input byte is saved along with the value of the internal counter(that is incremented each pass through the software timing loop). If theresult is zero, the systems waits (e.g., executes no operationinstructions) the same amount of time as if the data had to be saved,and the looping operation continues. The process continues until alleight inputs have changed at least twice, which enables measurement of afull ½ period of each input. Upon conclusion of the looping process,processor 26 analyzes the stored input bytes and internal counterstates. There should be 2 to 16 saved inputs (for the 8 total sensors ofFIG. 3) and counter states (if two or more inputs change at the sametime, they are saved simultaneously). As will be understood by one ofskill in the art, the stored values of the internal counter containsinformation determinative of the period of the signals received fromsensing elements 24. By proper subtraction of internal counter values attimes when an input bit has changed, the period may be calculated. Suchperiods calculated for each of the outputs of sensing elements isprovided by processor 26 to microprocessor 10 (see, e.g., FIG. 1). Fromsuch calculated periods, a measure of the received light intensities maybe calculated. In alternate embodiments, the frequency of the outputs ofthe TSL230 sensors is measured directly by a similar software loop asthe one described above. The outputs are monitored by the RISC processorin a software timing loop and are XORed with the previous input asdescribed above. If a transition occurs for a particular TSL230 input, acounter register for the particular TSL230 input is incremented. Thesoftware loop is executed for a pre-determined period of time and thefrequency of the input is calculated by dividing the number oftransitions by the pre-determined time and scaling the result. It willalso be apparent to one skilled in the art that more sophisticatedmeasurement schemes can also be implemented whereby both the frequencyand period are simultaneously measured by high speed RISC processorssuch as those of the Hitachi SH family.

[0086] It should be noted that the sensing circuitry and methodologyillustrated in FIG. 3 have been determined to provide a practical andexpedient manner in which to measure the light intensities received bysensing elements 24. In other embodiments, other circuits andmethodologies are employed (such other exemplary sensing schemes aredescribed elsewhere herein).

[0087] As discussed above with reference to FIG. 1, one or more offibers 7 measures light source 11, which may be through a neutraldensity filter, which serves to reduce the intensity of the receivedlight in order to maintain the intensity roughly in the range of theother received light intensities. A number of fibers 7 also are fromperimeter receiver fiber optics R1 to R3 (see, e.g., FIG. 2) and alsomay pass through neutral density filters. Such receiving fibers 7 serveto provide data from which angle/height information and/or surfacecharacteristics may be determined.

[0088] The remaining twelve fibers (of the illustrated embodiment'stotal of 16 fibers) of fibers 7 pass through color filters and are usedto produce the color measurement. In an embodiment, the color filtersare Kodak Sharp Cutting Wratten Gelatin Filters, which pass light withwavelengths greater than the cut-off value of the filter (i.e., redishvalues), and absorb light with wavelengths less than the cut-off valueof the filter (i.e., bluish values). “Sharp Cutting” filters areavailable in a wide variety of cut-off frequencies/wavelengths, and thecut-off values generally may be selected by proper selection of thedesired cut-off filter. In an embodiment, the filter cut-off values arechosen to cover the entire visible spectrum and, in general, to haveband spacings of approximately the visible band range (or other desiredrange) divided by the number of receivers/filters. As an example, 700nanometers minus 400 nanometers, divided by 11 bands (produced by twelvecolor receivers/sensors), is roughly 30 nanometer band spacing.

[0089] With an array of cut-off filters as described above, and withoutbeing bound by theory or the specific embodiments described herein, thereceived optical spectrum may be measured/calculated by subtracting thelight intensities of “adjacent” color receivers. For example, band 1(400 nm to 430 nm)=(intensity of receiver 12) minus (intensity ofreceiver 11), and so on for the remaining bands. Such an array ofcut-off filters, and the intensity values that may result from filteringwith such an array, are more fully described in connection with FIGS.13A to 14B.

[0090] It should be noted here that in alternate embodiments other colorfilter arrangements are utilized. For example, “notch” or bandpassfilters may be utilized, such as may be developed using Schottglass-type filters (whether constructed from separate longpass/shortpassfilters or otherwise) or notch interference filters such as thosemanufactured by Corion, etc.

[0091] In a preferred embodiment of the present invention, the specificcharacteristics of the light source, filters, sensors and fiber optics,etc., are normalized/calibrated by directing the probe towards, andmeasuring, a known color standard. Such normalization/calibration may beperformed by placing the probe in a suitable fixture, with the probedirected from a predetermined position (i.e., height and angle) from theknown color standard. Such measured normalization/calibration data maybe stored, for example, in a look-up table, and used by microprocessor10 to normalize or correct measured color or other data. Such proceduresmay be conducted at start-up, at regular periodic intervals, or byoperator command, etc. In particular embodiments, a large number ofmeasurements in may be taken on materials of particular characteristicsand processed and/or statistically analyzed or the like, with datarepresenting or derived from such measurements stored in memory (such asa look-up table or polynomial or other coefficients, etc.). Thereafter,based upon measurements of an object taken in accordance with thepresent invention, comparisons may be made with the stored data andassessments of the measured object made or predicted. In oneillustrative example, an assessment or prediction may be made of whetherthe object is wet or dry (having water or other liquid on its surface,wet paint, etc.) based on measurements in accordance with the presentinvention. In yet another illustrative example, an assessment orprediction of the characteristics of an underlying material, such as thepulpal tissue within a tooth may be made. Such capabilities may befurther enhanced by comparisons with measurements taken of the object atan earlier time, such as data taken of the tooth or other object at oneor more earlier points in time. Such comparisons based on suchhistorical data and/or stored data may allow highly useful assessmentsor predictions of the current or projected condition or status of thetooth, tissue or other object, etc. Many other industrial uses of suchsurface and subsurface assessment/prediction capabilities are possible.

[0092] What should be noted from the above description is that thereceiving and sensing fiber optics and circuitry illustrated in FIG. 3provide a practical and expedient way to determine the color and otheroptical or other characteristics by measuring the intensity of the lightreflected from the surface of the object being measured.

[0093] It also should be noted that such a system measures the spectralband of the reflected light from the object, and once measured suchspectral data may be utilized in a variety of ways. For example, suchspectral data may be displayed directly as intensity-wavelength bandvalues. In addition, tristmulus type values may be readily computed(through, for example, conventional matrix math), as may any otherdesired color values. In one particular embodiment useful in dentalapplications (such as for dental prostheses), the color data is outputin the form of a closest match or matches of dental shade guidevalue(s). In a preferred embodiment, various existing shade guides (suchas the shade guides produced by Vita Zahnfabrik) are characterized andstored in a look-up table, or in the graphics art industry Pantone colorreferences, and the color measurement data are used to select theclosest shade guide value or values, which may be accompanied by aconfidence level or other suitable factor indicating the degree ofcloseness of the match or matches, including, for example, what areknown as ΔE values or ranges of ΔE values, or criteria based on standarddeviations, such as standard deviation minimization. In still otherembodiments, the color measurement data are used (such as with look-uptables) to select materials for the composition of paint or ceramicssuch as for prosthetic teeth. There are many other uses of such spectraldata measured in accordance with the present invention.

[0094] It is known that certain objects such as human teeth mayfluoresce, and such optical characteristics also may be measured inaccordance with the present invention. A light source with anultraviolet component may be used to produce more accurate color/opticaldata with respect to such objects. Such data may be utilized to adjustthe amounts and or proportions or types of dental fluorescing materialsin dental restorations or prosthesis. In certain embodiments, atungsten/halogen source (such as used in a preferred embodiment) may becombined with a UV light source (such as a mercury vapor, xenon or otherfluorescent light source, etc.) to produce a light output capable ofcausing the object to fluoresce. Alternately, a separate UV lightsource, combined with a visible-light-blocking filter, may be used toilluminate the object. Such a UV light source may be combined with lightfrom a red LED (for example) in order to provide a visual indication ofwhen the UV light is on and also to serve as an aid for the directionalpositioning of the probe operating with such a light source. A secondmeasurement may be taken using the UV light source in a manner analogousto that described earlier, with the band of the red LED or othersupplemental light source being ignored. The second measurement may thusbe used to produce an indication of the fluorescence of the tooth orother object being measured. With such a UV light source, a silica fiberoptic (or other suitable material) typically would be required totransmit the light to the object (standard fiber optic materials such asglass and plastic in general do not propagate UV light in a desiredmanner, etc.).

[0095] As described earlier, in certain preferred embodiments thepresent invention utilizes a plurality of perimeter receiver fiberoptics spaced apart from and around a central source fiber optic tomeasure color and determine information regarding the height and angleof the probe with respect to the surface of the object being measured,which may include other surface characteristic information, etc. Withoutbeing bound by theory, certain principles underlying certain aspects ofthe present invention will now be described with reference to FIGS. 4Ato 4C.

[0096]FIG. 4A illustrates a typical step index fiber optic consisting ofa core and a cladding. For this discussion, it is assumed that the corehas an index of refraction of n₀ and the cladding has an index ofrefraction of n₁. Although the following discussion is directed to “stepindex” fibers, it will be appreciated by those of skill in the art thatsuch discussion generally is applicable for gradient index fibers aswell.

[0097] In order to propagate light without loss, the light must beincident within the core of the fiber optic at an angle greater than thecritical angle, which may be represented as Sin⁻¹{n₁/n₀}, where n₀ isthe index of refraction of the core and n₁ is the index of refraction ofthe cladding. Thus, all light must enter the fiber at an acceptanceangle equal to or less than phi, with phi=2×Sin⁻¹{{square root}(n₀ ²−n₁²)}, or it will not be propagated in a desired manner.

[0098] For light entering a fiber optic, it must enter within theacceptance angle phi. Similarly, when the light exits a fiber optic, itwill exit the fiber optic within a cone of angle phi as illustrated inFIG. 4A. The value {square root}(n₀ ²−n₁ ²) is referred to as theaperture of the fiber optic. For example, a typical fiber optic may havean aperture of 0.5, and an acceptance angle of 60°.

[0099] Consider using a fiber optic as a light source. One end isilluminated by a light source (such as light source 11 of FIG. 1), andthe other is held near a surface. The fiber optic will emit a cone oflight as illustrated in FIG. 4A. If the fiber optic is heldperpendicular to a surface it will create a circular light pattern onthe surface. As the fiber optic is raised, the radius r of the circlewill increase. As the fiber optic is lowered, the radius of the lightpattern will decrease. Thus, the intensity of the light (light energyper unit area) in the illuminated circular area will increase as thefiber optic is lowered and will decrease as the fiber optic is raised.

[0100] The same principle generally is true for a fiber optic beingutilized as a receiver. Consider mounting a light sensor on one end of afiber optic and holding the other end near an illuminated surface. Thefiber optic can only propagate light without loss when the lightentering the fiber optic is incident on the end of the fiber optic nearthe surface if the light enters the fiber optic within its acceptanceangle phi. A fiber optic utilized as a light receiver near a surfacewill only accept and propagate light from the circular area of radius ron the surface. As the fiber optic is raised from the surface, the areaincreases. As the fiber optic is lowered to the surface, the areadecreases.

[0101] Consider two fiber optics parallel to each other as illustratedin FIG. 4B. For simplicity of discussion, the two fiber opticsillustrated are identical in size and aperture. The followingdiscussion, however, generally would be applicable for fiber optics thatdiffer in size and aperture. One fiber optic is a source fiber optic,the other fiber optic is a receiver fiber optic. As the two fiber opticsare held perpendicular to a surface, the source fiber optic emits a coneof light that illuminates a circular area of radius r. The receiverfiber optic can only accept light that is within its acceptance anglephi, or only light that is received within a cone of angle phi. If theonly light available is that emitted by the source fiber optic, then theonly light that can be accepted by the receiver fiber optic is the lightthat strikes the surface at the intersection of the two circles asillustrated in FIG. 4C. As the two fiber optics are lifted from thesurface, the proportion of the intersection of the two circular areasrelative to the circular area of the source fiber optic increases. Asthey near the surface, the proportion of the intersection of the twocircular areas to the circular area of the source fiber optic decreases.If the fiber optics are held too close to the surface (i.e., at or belowa “critical height” h_(c)), the circular areas will no longer intersectand no light emitted from the source fiber optic will be received by thereceiver fiber optic.

[0102] As discussed earlier, the intensity of the light in the circulararea illuminated by the source fiber increases as the fiber is loweredto the surface. The intersection of the two cones, however, decreases asthe fiber optic pair is lowered. Thus, as the fiber optic pair islowered to a surface, the total intensity of light received by thereceiver fiber optic increases to a maximal value, and then decreasessharply as the fiber optic pair is lowered still further to the surface.Eventually, the intensity will decrease essentially to zero at or belowthe critical height h_(c) (assuming the object being measured is nottranslucent, as described more fully herein), and will remainessentially zero until the fiber optic pair is in contact with thesurface. Thus, as a source-receiver pair of fiber optics as describedabove are positioned near a surface and as their height is varied, theintensity of light received by the receiver fiber optic reaches amaximal value at a peaking or “peaking height” h_(p).

[0103] Again without being bound by theory, an interesting property ofthe peaking height h_(p) has been observed. The peaking height h_(p) isa function primarily of the geometry of fixed parameters, such as fiberapertures, fiber diameters and fiber spacing. Since the receiver fiberoptic in the illustrated arrangement is only detecting a maximum valueand not attempting to quantify the value, its maximum in general isindependent of the surface color. It is only necessary that the surfacereflect sufficient light from the intersecting area of the source andreceiver fiber optics to be within the detection range of the receiverfiber optic light sensor. Thus, in general red or green or blue or anycolor surface will all exhibit a maximum at the same peaking heighth_(p).

[0104] Although the above discussion has focused on two fiber opticsperpendicular to a surface, similar analysis is applicable for fiberoptic pairs at other angles. When a fiber optic is not perpendicular toa surface, it generally illuminates an elliptical area. Similarly, theacceptance area of a receiver fiber optic generally becomes elliptical.As the fiber optic pair is moved closer to the surface, the receiverfiber optic also will detect a maximal value at a peaking heightindependent of the surface color or characteristics. The maximalintensity value measured when the fiber optic pair is not perpendicularto the surface, however, will be less than the maximal intensity valuemeasured when the fiber optic pair is perpendicular to the surface.

[0105] Referring now to FIGS. 5A and 5B, the intensity of light receivedas a fiber optic source-receiver pair is moved to and from a surfacewill now be described. FIG. 5A illustrates the intensity of the receivedlight as a function of time. Corresponding FIG. 5B illustrates theheight of the fiber optic pair from the surface of the object beingmeasured. FIGS. 5A and 5B illustrate (for ease of discussion) arelatively uniform rate of motion of the fiber optic pair to and fromthe surface of the object being measured (although similarillustrations/analysis would be applicable for non-uniform rates aswell).

[0106]FIG. 5A illustrates the intensity of received light as the fiberoptic pair is moved to and then from a surface. While FIG. 5Aillustrates the intensity relationship for a single receiver fiberoptic, similar intensity relationships would be expected to be observedfor other receiver fiber optics, such as, for example, the multiplereceiver fiber optics of FIGS. 1 and 2. In general with the preferredembodiment described above, all fifteen fiber optic receivers (of fibers7) will exhibit curves similar to that illustrated in FIG. 5A.

[0107]FIG. 5A illustrates five regions. In region 1, the probe is movedtowards the surface of the object being measured, which causes thereceived light intensity to increase. In region 2, the probe is movedpast the peaking height, and the received light intensity peaks and thenfalls off sharply. In region 3, the probe essentially is in contact withthe surface of the object being measured. As illustrated, the receivedintensity in region 3 will vary depending upon the translucence of theobject being measured. If the object is opaque, the received lightintensity will be very low, or almost zero (perhaps out of range of thesensing circuitry). If the object is translucent, however, the lightintensity will be quite high, but in general should be less than thepeak value. In region 4, the probe is lifted and the light intensityrises sharply to a maximum value. In region 5, the probe is liftedfurther away from the object, and the light intensity decreases again.

[0108] As illustrated, two peak intensity values (discussed as P1 and P2below) should be detected as the fiber optic pair moves to and from theobject at the peaking height h_(p). If peaks P1 and P2 produced by areceiver fiber optic are the same value, this generally is an indicationthat the probe has been moved to and from the surface of the object tobe measured in a consistent manner. If peaks P1 and P2 are of differentvalues, then these may be an indication that the probe was not moved toand from the surface of the object in a desired manner, or that thesurface is curved or textured, as described more fully herein. In such acase, the data may be considered suspect and rejected. In addition,peaks P1 and P2 for each of the perimeter fiber optics (see, e.g., FIG.2) should occur at the same height (assuming the geometric attributes ofthe perimeter fiber optics, such as aperture, diameter and spacing fromthe source fiber optic, etc.). Thus, the perimeter fiber optics of aprobe moved in a consistent, perpendicular manner to and from thesurface of the object being measured should have peaks P1 and P2 thatoccur at the same height. Monitoring receiver fibers from the perimeterreceiver fiber optics and looking for simultaneous (or near,simultaneous, e.g., within a predetermined range) peaks P1 and P2provides a mechanism for determining if the probe is held at a desiredperpendicular angle with respect to the object being measured.

[0109] In addition, the relative intensity level in region 3 serves asan indication of the level of translucency of the object being measured.Again, such principles generally are applicable to the totality ofreceiver fiber optics in the probe (see, e.g., fibers 7 of FIGS. 1 and3). Based on such principles, measurement techniques that may beapplicable with respect to embodiments disclosed herein will now bedescribed.

[0110]FIG. 6 is a flow chart illustrating a general measuring techniquethat may be used in accordance with certain embodiments of the presentinvention. Step 49 indicates the start or beginning of a color/opticalmeasurement. During step 49, any equipment initialization, diagnostic orsetup procedures may be performed. Audio or visual information or otherindicia may be given to the operator to inform the operator that thesystem is available and ready to take a measurement. Initiation of thecolor/optical measurement commences by the operator moving the probetowards the object to be measured, and may be accompanied by, forexample, activation of switch 17 (see FIG. 1).

[0111] In step 50, the system on a continuing basis monitors theintensity levels for the receiver fiber optics (see, e.g., fibers 7 ofFIG. 1). If the intensity is rising, step 50 is repeated until a peak isdetected. If a peak is detected, the process proceeds to step 52. Instep 52, measured peak intensity P1, and the time at which such peakoccurred, are stored in memory (such as in memory included as a part ofmicroprocessor 10), and the process proceeds to step 54. In step 54, thesystem continues to monitor the intensity levels of the receiver fiberoptics. If the intensity is falling, step 54 is repeated. If a “valley”or plateau is detected (i.e., the intensity is no longer falling, whichgenerally indicates contact or near contact with the object), then theprocess proceeds to step 56. In step 56, the measured surface intensity(IS) is stored in memory, and the process proceeds to step 58. In step58, the system continues to monitor the intensity levels of the receiverfibers. If the intensity is rising, step 58 is repeated until a peak isdetected. If a peak is detected, the process proceeds to step 60. Instep 60, measured peak intensity P2, and the time at which such peakoccurred, are stored in memory, and the process proceeds to step 62. Instep 62, the system continues to monitor the intensity levels of thereceiver fiber optics. Once the received intensity levels begin to fallfrom peak P2, the system perceives that region 5 has been entered (see,e.g., FIG. 5A), and the process proceeds to step 64.

[0112] In step 64, the system, under control of microprocessor 10, mayanalyze the collected data taken by the sensing circuitry for thevarious receiver fiber optics. In step 64, peaks P1 and P2 of one ormore of the various fiber optics may be compared. If any of peaks P1 andP2 for any of the various receiver fiber optics have unequal peakvalues, then the data may be rejected, and the entire color measuringprocess repeated. Again, unequal values of peaks P1 and P2 may beindicative, for example, that the probe was moved in a non-perpendicularor otherwise unstable manner (i.e., angular or lateral movement), and,for example, peak P1 may be representative of a first point on theobject, while peak P2 may be representative of a second point on theobject. As the data is suspect, in a preferred embodiment of the presentinvention, data taken in such circumstances are rejected in step 64.

[0113] If the data are not rejected in step 64, the process proceeds tostep 66. In step 66, the system analyzes the data taken from theneutral-density-filtered receivers from each of the perimeter fiberoptics (e.g., R1 to R3 of FIG. 2). If the peaks of the perimeter fiberoptics did not occur at or about the same point in time, this may beindicative, for example, that the probe was not held perpendicular tothe surface of the object being measured. As non-perpendicular alignmentof the probe with the surface of the object being measured may causesuspect results, in a preferred embodiment of the present invention,data taken in such circumstances are rejected in step 66. In onepreferred embodiment, detection of simultaneous or near simultaneouspeaking (peaking within a predetermined range of time) serves as anacceptance criterion for the data, as perpendicular alignment generallyis indicated by simultaneous or near simultaneous peaking of theperimeter fiber optics. In other embodiments, step 66 includes ananalysis of peak values P1 and P2 of the perimeter fiber optics. In suchembodiments, the system seeks to determine if the peak values of theperimeter fiber optics (perhaps normalized with any initial calibrationdata) are equal within a defined range. If the peak values of theperimeter fiber optics are within the defined range, the data may beaccepted, and if not, the data may be rejected. In still otherembodiments, a combination of simultaneous peaking and equal valuedetection are used as acceptance/rejection criteria for the data, and/orthe operator may have the ability (such as through key pad switches 12)to control one or more of the acceptance criteria ranges. With suchcapability, the sensitivity of the system may be controllably altered bythe operator depending upon the particular application and operativeenvironment, etc.

[0114] If the data are not rejected in step 66, the process proceeds tostep 68. In step 68, the color data may be processed in a desired mannerto produce output color/optical measurement data. For example, such datamay be normalized in some manner, or adjusted based on temperaturecompensation, or translucency data, or gloss data or surface texturedata or non-perpendicular angle data other data detected by the system.The data also may be converted to different display or other formats,depending on the intended use of the data. In addition, the dataindicative of the translucence of the object and/or glossiness of theobject also may be quantified and/or displayed in step 68. After step68, the process may proceed to starting step 49, or the process may beterminated, etc. As indicated previously, such data also may be comparedwith previously-stored data for purposes of making assessments orpredictions, etc., of a current or future condition or status.

[0115] In accordance with the process illustrated in FIG. 6, three lightintensity values (P1, P2 and IS) are stored per receiver fiber optic tomake color and translucency, etc., measurements. If stored peak valuesP1 and P2 are not equal (for some or all of the receivers), this is anindication that the probe was not held steady over one area, and thedata may be rejected (in other embodiments, the data may not berejected, although the resulting data may be used to produce an averageof the measured data). In addition, peak values P1 and P2 for the threeneutral density perimeter fiber optics should be equal or approximatelyequal; if this is not the case, then this is an indication that theprobe was not held perpendicular or a curved surface is being measured.In other embodiments, the system attempts to compensate for curvedsurfaces and/or non-perpendicular angles. In any event, if the systemcannot make a color/optical measurement, or if the data is rejectedbecause peak values P1 and P2 are unequal to an unacceptable degree orfor some other reason, then the operator is notified so that anothermeasurement or other action may be taken (such as adjust thesensitivity).

[0116] With a system constructed and operating as described above,color/optical measurements may be taken of an object, with accepted datahaving height and angular dependencies removed. Data not taken at thepeaking height, or data not taken with the probe perpendicular to thesurface of the object being measured, etc., are rejected in certainembodiments. In other embodiments, data received from the perimeterfiber optics may be used to calculate the angle of the probe withrespect to the surface of the object being measured, and in suchembodiments non-perpendicular or curved surface data may be compensatedinstead of rejected. It also should be noted that peak values P1 and P2for the neutral density perimeter fiber optics provide a measurement ofthe luminance (gray value) of the surface of the object being measured,and also may serve to quantify the color value.

[0117] The translucency of the object being measured may be quantifiedas a ratio or percentage, such as, for example, (IS/P1)×100%. In otherembodiments, other methods of quantifying translucency data provided inaccordance with the present invention are utilized, such as some otherarithmetic function utilizing IS and P1 or P2, etc. Translucenceinformation, as would be known to those in the art, could be used toquantify and/or adjust the output color data, etc.

[0118] In another particular aspect of the present invention, datagenerated in accordance with the present invention may be used toimplement an automated material mixing/generation machine and/or method.Certain objects/materials, such as dental prostheses or fillings, aremade from porcelain or other powders/resins/materials or tissuesubstitutes that may be combined in the correct ratios or modified withadditives to form the desired color of the object/prosthesis. Certainpowders often contain pigments that generally obey Beer's law and/or actin accordance with Kubelka-Munk equations and/or Saunderson equations(if needed) when mixed in a recipe. Color and other data taken from ameasurement in accordance with the present invention may be used todetermine or predict desired quantities of pigment or other materialsfor the recipe. Porcelain powders and other materials are available indifferent colors, opacities, etc. Certain objects, such as dentalprostheses, may be layered to simulate the degree of translucency of thedesired object (such as to simulate a human tooth). Data generated inaccordance with the present invention also may be used to determine thethickness and position of the porcelain or other material layers to moreclosely produce the desired color, translucency, surfacecharacteristics, etc. In addition, based on fluorescence data for thedesired object, the material recipe may be adjusted to include a desiredquantity of fluorescing-type material. In yet other embodiments, surfacecharacteristics (such as texture) information (as more fully describedherein) may be used to add a texturing material to the recipe, all ofwhich maybe carried out in accordance with the present invention. In yetother embodiments, the degree of surface polish to the prosthesis may bemonitored or adjusted, based on gloss data derived in accordance withthe present invention.

[0119] For more information regarding such pigment-material recipe typetechnology, reference may be made to: “The Measurement of Appearance,”Second Edition, edited by Hunter and Harold, copyright 1987; “Principlesof Color Technology,” by Billmeyer and Saltzman, copyright 1981; and“Pigment Handbook,” edited by Lewis, copyright 1988. All of theforegoing are believed to have been published by John Wiley & Sons,Inc., New York, N.Y., and all of which are hereby incorporated byreference.

[0120] In certain operative environments, such as dental applications,contamination of the probe is of concern. In certain embodiments of thepresent invention, implements to reduce such contamination are provided.

[0121]FIGS. 7A and 7B illustrate a protective cap that may be used tofit over the end of probe tip 1. Such a protective cap consists of body80, the end of which is covered by optical window 82, which in apreferred embodiment consists of a structure having a thin sapphirewindow. In a preferred embodiment, body 80 consists of stainless steel.Body 80 fits over the end of probe tip 1 and may be held into place by,for example, indentations formed in body 80, which fit with ribs 84(which may be a spring clip or other retainer) formed on probe tip 1. Inother embodiments, other methods of affixing such a protective cap toprobe tip 1 are utilized. The protective cap may be removed from probetip 1 and sterilized in a typical autoclave, hot steam, chemiclave orother sterilizing system.

[0122] The thickness of the sapphire window should be less than thepeaking height of the probe in order to preserve the ability to detectpeaking in accordance with the present invention, and preferably has athickness less than the critical height at which the source/receivercones overlap (see FIGS. 4B and 4C). It also is believed that sapphirewindows may be manufactured in a reproducible manner, and thus any lightattenuation from one cap to another may be reproducible. In addition,any distortion of the color/optical measurements produced by thesapphire window may be calibrated out by microprocessor 10.

[0123] Similarly, in other embodiments body 80 has a cap with a hole inthe center (as opposed to a sapphire window), with the hole positionedover the fiber optic source/receivers The cap with the hole serves toprevent the probe from coming into contact with the surface, therebyreducing the risk of contamination. It should be noted that, with suchembodiments, the hole is positioned so that the light from/to the lightsource/receiver elements of the probe tip is not adversely affected bythe cap.

[0124]FIGS. 8A and 8B illustrate another embodiment of a removable probetip that may be used to reduce contamination in accordance with thepresent invention. As illustrated in FIG. 8A, probe tip 88 is removable,and includes four (or a different number, depending upon theapplication) fiber optic connectors 90, which are positioned withinoptical guard 92 coupled to connector 94. Optical guard 92 serves toprevent “cross talk” between adjacent fiber optics. As illustrated inFIG. 8B, in this embodiment removable tip 88 is secured in probe tiphousing 93 by way of spring clip 96 (other removable retainingimplements are utilized in other embodiments). Probe tip housing 93 maybe secured to base connector 95 by a screw or other conventionalfitting. It should be noted that, with this embodiment, different sizetips may be provided for different applications, and that an initialstep of the process may be to install the properly-sized (or fitted tip)for the particular application. Removable tip 88 also may be sterilizedin a typical autoclave, hot steam, chemiclave or other sterilizingsystem, or disposed of. In addition, the entire probe tip assembly isconstructed so that it may be readily disassembled for cleaning orrepair. In certain embodiments the light source/receiver elements of theremovable tip are constructed of glass, silica or similar materials,thereby making them particularly suitable for autoclave or similar hightemperature/pressure cleaning methods, which in certain otherembodiments the light source/receiver elements of the removable tip areconstructed of plastic or other similar materials, which may be of lowercost, thereby making them particularly suitable for disposable-typeremovable tips, etc.

[0125] In still other embodiments, a plastic, paper or other type shield(which may be disposable, cleanable/reusable or the like) may be used inorder to address any contamination concerns that may exist in theparticular application. In such embodiments, the methodology may includepositioning such a shield over the probe tip prior to takingcolor/optical measurements, and may include removing anddisposing/cleaning the shield after taking color/optical measurements,etc.

[0126] A further embodiment of the present invention utilizing analternate removable probe tip will now be described with reference toFIGS. 23A-23C. As illustrated in FIG. 23A, this embodiment utilizesremovable, coherent light conduit 340 as a removable tip. Light conduit340 is a short segment of a light conduit that preferably may be a fusedbundle of small fiber optics, in which the fibers are held essentiallyparallel to each other, and the ends of which are highly polished.Cross-section 350 of light conduit 340 is illustrated in FIG. 23B. Lightconduits similar to light conduit 340 have been utilized in what areknown as borescopes, and also have been utilized in medical applicationssuch as endoscopes.

[0127] Light conduit 340 in this embodiment serves to conduct light fromthe light source to the surface of the object being measured, and alsoto receive reflected light from the surface and conduct it to lightreceiver fiber optics 346 in probe handle 344. Light conduit 340 is heldin position with respect to fiber optics 346 by way or compression jaws342 or other suitable fitting or coupled that reliably positions lightconduit 340 so as to couple light effectively to/from fiber optics 346.Fiber optics 346 may be separated into separate fibers/light conduits348, which may be coupled to appropriate light sensors, etc., as withpreviously described embodiments.

[0128] In general, the aperture of the fiber optics used in lightconduit 340 may be chosen to match the aperture of the fiber optics forthe light source and the light receivers or alternately the lightconduit aperture could be greater than or equal to the largest source orreceiver aperture. Thus, the central part of the light conduit mayconduct light from the light source and illuminate the surface as if itconstituted a single fiber within a bundle of fibers. Similarly, theouter portion of the light conduit may receive reflected light andconduct it to light receiver fiber optics as if it constituted singlefibers. Light conduit 340 has ends that preferably are highly polishedand cut perpendicular, particularly the end coupling light to fiberoptics 346. Similarly, the end of fiber optics 346 abutting lightconduit 340 also is highly polished and cut perpendicular to a highdegree of accuracy in order to minimize light reflection and cross talkbetween the light source fiber optic and the light receiver fiber opticsand between adjacent receiver fiber optics. Light conduit 340 offerssignificant advantages including in the manufacture and installation ofsuch a removable tip. For example, the probe tip need not beparticularly aligned with the probe tip holder; rather, it only needs tobe held against the probe tip holder such as with a compressionmechanism (such as with compression jaws 342) so as to couple lighteffectively to/from fiber optics 346. Thus, such a removable tipmechanism may be implemented without alignment tabs or the like, therebyfacilitating easy installation of the removable probe tip. Such an easyinstallable probe tip may thus be removed and cleaned prior toinstallation, thereby facilitating use of the color/optical measuringapparatus by dentists, medical professions or others working in anenvironment in which contamination may be a concern. Light conduit 340also may be implemented, for example, as a small section of lightconduit, which may facilitate easy and low cost mass production and thelike.

[0129] A further embodiment of such a light conduit probe tip isillustrated as light conduit 352 in FIG. 23C. Light conduit 352 is alight conduit that is narrower on one end (end 354) than the other end(end 356). Contoured/tapered light conduits such as light conduit 352may be fabricated by heating and stretching a bundle of small fiberoptics as part of the fusing process. Such light conduits have anadditional interesting property of magnification or reduction. Suchphenomena result because there are the same number of fibers in bothends. Thus, light entering narrow end 354 is conducted to wider end 356,and since wider end 356 covers a larger area, it has a magnifyingaffect.

[0130] Light conduit 352 of FIG. 23C may be utilized in a manner similarto light conduit 340 (which in general may be cylindrical) of FIG. 23A.Light conduit 352, however, measures smaller areas because of itsreduced size at end 354. Thus, a relatively larger probe body may bemanufactured where the source fiber optic is spaced widely from thereceiver fiber optics, which may provide an advantage in reduced lightreflection and cross talk at the junction, while still maintaining asmall probe measuring area. Additionally, the relative sizes of narrowend 354 of light conduit 352 may be varied. This enables the operator toselect the size/characteristic of the removable probe tip according tothe conditions in the particular application. Such ability to selectsizes of probe tips provides a further advantage in making opticalcharacteristics measurements in a variety of applications and operativeenvironments.

[0131] As should be apparent to those skilled in the art in view of thedisclosures herein, light conduits 340 and 356 of FIGS. 23A and 23C neednot necessarily be cylindrical/tapered as illustrated, but may be curvedsuch as for specialty applications, in which a curved probe tip may beadvantageously employed (such as in a confined, or hard-to-reach place).It also should be apparent that light conduit 352 of FIG. 23C may bereversed (with narrow end 354 coupling light into fiber optics 346,etc., and wide end 356 positioned in order to take measurements) inorder to cover larger areas.

[0132] With reference to FIG. 9, a tristimulus embodiment will now bedescribed, which may aid in the understanding of, or may be used inconjunction with, certain embodiments disclosed herein. In general, theoverall system depicted in FIG. 1 and discussed in detail elsewhereherein may be used with this embodiment. FIG. 9 illustrates a crosssection of the probe tip fiber optics used in this embodiment.

[0133] Probe tip 100 includes central source fiber optic 106, surroundedby (and spaced apart from) three perimeter receiver fiber optics 104 andthree color receiver fiber optics 102. Three perimeter receiver fiberoptics 104 are optically coupled to neutral density filters and serve asheight/angle sensors in a manner analogous to the embodiment describeabove. Three color receiver fiber optics are optically coupled tosuitable tristimulus filters, such as red, green and blue filters. Withthis embodiment, a measurement may be made of tristimulus color valuesof the object, and the process described with reference to FIG. 6generally is applicable to this embodiment. In particular, perimeterfiber optics 104 may be used to detect simultaneous peaking or otherwisewhether the probe is perpendicular to the object being measured.

[0134]FIG. 10A illustrates another such embodiment, similar to theembodiment discussed with reference to FIG. 9. Probe tip 100 includescentral source fiber optic 106, surrounded by (and spaced apart from)three perimeter receiver fiber optics 104 and a plurality of colorreceiver fiber optics 102. The number of color receiver fiber optics102, and the filters associated with such receiver fiber optics 102, maybe chosen based upon the particular application. As with the embodimentof FIG. 9, the process described with reference to FIG. 6 generally isapplicable to this embodiment.

[0135]FIG. 10B illustrates another such embodiment in which there are aplurality of receiver fiber optics that surround central source fiberoptic 240. The receiver fiber optics are arranged in rings surroundingthe central source fiber optic. FIG. 10B illustrates three rings ofreceiver fiber optics (consisting of fiber optics 242, 244 and 246,respectively), in which there are six receiver fiber optics per ring.The rings may be arranged in successive larger circles as illustrated tocover the entire area of the end of the probe, with the distance fromeach receiver fiber optic within a given ring to the central fiber opticbeing equal (or approximately so). Central fiber optic 240 is utilizedas the light source fiber optic and is connected to the light source ina manner similar to light source fiber optic 5 illustrated in FIG. 1.

[0136] The plurality of receiver fiber optics are each coupled to two ormore fiber optics in a manner similar to the arrangement illustrated inFIG. 1 for splicing connector 4. One fiber optic from such a splicingconnector for each receiver fiber optic passes through a neutral densityfilter and then to light sensor circuitry similar to the light sensorcircuitry illustrated in FIG. 3. A second fiber optic from the splicingconnector per receiver fiber optic passes through a Sharp CuttingWrattan Gelatin Filter (or notch filter as previously described) andthen to light sensor circuitry as discussed elsewhere herein. Thus, eachof the receiver fiber optics in the probe tip includes both colormeasuring elements and neutral light measuring or “perimeter” elements.

[0137]FIG. 10D illustrates the geometry of probe 260 (such as describedabove) illuminating an area on flat diffuse surface 272. Probe 260creates light pattern 262 that is reflected diffusely from surface 272in uniform hemispherical pattern 270. With such a reflection pattern,the reflected light that is incident upon the receiving elements in theprobe will be equal (or nearly equal) for all elements if the probe isperpendicular to the surface as described above herein.

[0138]FIG. 10C illustrates a probe illuminating rough surface 268 or asurface that reflects light unevenly. The reflected light will exhibithot spots or regions 266 where the reflected light intensity isconsiderably greater than it is on other areas 264. The reflected lightpattern will be uneven when compared to a smooth surface as illustratein FIG. 10D.

[0139] Since a probe as illustrated in FIG. 10B has a plurality ofreceiver fiber optics arranged over a large surface area, the probe maybe utilized to determine the surface texture of the surface as well asbeing able to measure the color and translucency, etc., of the surfaceas described earlier herein. If the light intensity received by thereceiver fiber optics is equal for all fiber optics within a given ringof receiver fiber optics, then generally the surface is smooth. If,however, the light intensity of receiver fibers in a ring varies withrespect to each other, then generally the surface is rough. By comparingthe light intensities measured within receiver fiber optics in a givenring and from ring to ring, the texture and other characteristics of thesurface may be quantified.

[0140]FIG. 11 illustrates an embodiment of the present invention inwhich linear optical sensors and a color gradient filter are utilizedinstead of light sensors 8 (and filters 22, etc.). Receiver fiber optics7, which may be optically coupled to probe tip 1 as with the embodimentof FIG. 1, are optically coupled to linear optical sensor 112 throughcolor gradient filter 110. In this embodiment, color gradient filter 110may consist of series of narrow strips of cut-off type filters on atransparent or open substrate, which are constructed so as topositionally correspond to the sensor areas of linear optical sensor112. An example of a commercially available linear optical sensor 112 isTexas Instruments part number TSL213, which has 61 photo diodes in alinear array. Light receiver fiber optics 7 are arranged correspondinglyin a line over linear optical sensor 112. The number of receiver fiberoptics may be chosen for the particular application, so long as enoughare included to more or less evenly cover the full length of colorgradient filter 110. With this embodiment, the light is received andoutput from receiver fiber optics 7, and the light received by linearoptical sensor 112 is integrated for a short period of time (determinedby the light intensity, filter characteristics and desired accuracy).The output of linear array sensor 112 is digitized by ADC 114 and outputto microprocessor 116 (which may the same processor as microprocessor 10or another processor).

[0141] In general, with the embodiment of FIG. 11, perimeter receiverfiber optics may be used as with the embodiment of FIG. 1, and ingeneral the process described with reference to FIG. 6 is applicable tothis embodiment.

[0142]FIG. 12 illustrates an embodiment of the present invention inwhich a matrix optical sensor and a color filter grid are utilizedinstead of light sensors 8 (and filters 22, etc.). Receiver fiber optics7, which may be optically coupled to probe tip 1 as with the embodimentof FIG. 1, are optically coupled to matrix optical sensor 122 throughfilter grid 120. Filter grid 120 is a filter array consisting of anumber of small colored spot filters that pass narrow bands of visiblelight. Light from receiver fiber optics 7 pass through correspondingfilter spots to corresponding points on matrix optical sensor 122. Inthis embodiment, matrix optical sensor 122 may be a monochrome opticalsensor array, such as CCD-type or other type of light sensor elementsuch as may be used in a video camera. The output of matrix opticalsensor 122 is digitized by ADC 124 and output to microprocessor 126(which may the same processor as microprocessor 10 or anotherprocessor). Under control of microprocessor 126, matrix optical sensor126 collects data from receiver fiber optics 7 through color filter grid120.

[0143] In general, with the embodiment of FIG. 12, perimeter receiverfiber optics may be used as with the embodiment of FIG. 1, and ingeneral the process described with reference to FIG. 6 also isapplicable to this embodiment.

[0144] In general with the embodiments of FIGS. 11 and 12, the colorfilter grid may consist of sharp cut off filters as described earlier orit may consist of notch filters. As will be apparent to one skilled inthe art, they may also be constructed of a diffraction grating andfocusing mirrors such as those utilized in conventional monochromators.

[0145] As will be clear from the foregoing description, with the presentinvention a variety of types of spectral color/optical photometers (ortristimulus-type colorimeters) may be constructed, with perimeterreceiver fiber optics used to collect color/optical data essentiallyfree from height and angular deviations. In addition, in certainembodiments, the present invention enables color/optical measurements tobe taken at a peaking height from the surface of the object beingmeasured, and thus color/optical data may be taken without physicalcontact with the object being measured (in such embodiments, thecolor/optical data is taken only by, passing the probe through region 1and into region 2, but without necessarily going into region 3 of FIGS.5A and 5B). Such embodiments may be utilized if contact with the surfaceis undesirable in a particular application. In the embodiments describedearlier, however, physical contact (or near physical contact) of theprobe with the object may allow all five regions of FIGS. 5A and 5B tobe utilized, thereby enabling measurements to be taken such thattranslucency information also may be obtained. Both types of embodimentsgenerally are within the scope of the invention described herein.

[0146] Additional description will now be provided with respect tocut-off filters of the type described in connection with the preferredembodiment(s) of FIGS. 1 and 3 (such as filters 22 of FIG. 3). FIG. 13Aillustrates the properties of a single Kodak Sharp Cutting WrattenGelatin Filter discussed in connection with FIG. 3. Such a cut-offfilter passes light below a cut-off frequency (i.e., above a cut-offwavelength). Such filters may be manufactured to have a wide range ofcut-off frequencies/wavelengths. FIG. 13B illustrates a number of suchfilters, twelve in a preferred embodiment, with cut-offfrequencies/wavelength chosen so that essentially the entire visibleband is covered by the collection of cut-off filters.

[0147]FIGS. 14A and 14B illustrate exemplary intensity measurementsusing a cut-off filter arrangement such as illustrated in FIG. 13B,first in the case of a white surface being measured (FIG. 14A), and alsoin the case of a blue surface being measured (FIG. 14B). As illustratedin FIG. 14A, in the case of a white surface, the neutrally filteredperimeter fiber optics, which are used to detect height and angle, etc.,generally will produce the highest intensity (although this depends atleast in part upon the characteristics of the neutral density filters).As a result of the stepped cut-off filtering provided by filters havingthe characteristics illustrated in FIG. 13B, the remaining intensitieswill gradually decrease in value as illustrated in FIG. 14A. In the caseof a blue surface, the intensities will decrease in value generally asillustrated in FIG. 14B. Regardless of the surface, however, theintensities out of the filters will always decrease in value asillustrated, with the greatest intensity value being the output of thefilter having the lowest wavelength cut-off value (i.e., passes allvisible light up to blue), and the lowest intensity value being theoutput of the filter having the highest wavelength cut-off (i.e., passesonly red visible light). As will be understood from the foregoingdescription, any color data detected that does not fit the decreasingintensity profiles of FIGS. 14A and 14B may be detected as anabnormality, and in certain embodiments detection of such a conditionresults in data rejection, generation of an error message or initiationof a diagnostic routine, etc.

[0148] Reference should be made to the FIGS. 1 and 3 and the relateddescription for a detailed discussion of how such a cut-off filterarrangement may be utilized in accordance with the present invention.

[0149]FIG. 15 is a flow chart illustrating audio tones that may be usedin certain preferred embodiments of the present invention. It has beendiscovered that audio tones (such as tones, beeps, voice or the likesuch as will be described) present a particularly useful and instructivemeans to guide an operator in the proper use of a color measuring systemof the type described herein.

[0150] The operator may initiate a color/optical measurement byactivation of a switch (such as switch 17 of FIG. 1). at step 150.Thereafter, if the system is ready (set-up, initialized, calibrated,etc.), a lower-the-probe tone is emitted (such as through speaker 16 ofFIG. 1) at step 152. The system attempts to detect peak intensity P1 atstep 154. If a peak is detected, at step 156 a determination is madewhether the measured peak P1 meets the applicable criteria (such asdiscussed above in connection with FIGS. 5A, 5B and 6). If the measuredpeak P1 is accepted, a first peak acceptance tone is generated at step160. If the measured peak P1 is not accepted, an unsuccessful tone isgenerated at step 158, and the system may await the operator to initiatea further color/optical measurement. Assuming that the first peak wasaccepted, the system attempts to detect peak intensity P2 at step 162.If a second peak is detected at step 164 a determination is made whetherthe measured peak P2 meets the applicable criteria. If the measured peakP2 is accepted the process proceeds to color calculation step 166 (inother embodiments a second peak acceptance tone also is generated atstep 166). If the measured peak P2 is not accepted an unsuccessful toneis generated at step 158, and the system may await the operator toinitiate a further, color/optical measurement. Assuming that the secondpeak was accepted, a color/optical calculation is made at step 166 (suchas, for example, microprocessor 10 of FIG. 1 processing the data outputfrom light sensors 8, etc.). At step 168, a determination is madewhether the color calculation meets the applicable criteria. If thecolor calculation is accepted, a successful tone is generated at step170. If the color calculation is not accepted, an unsuccessful tone isgenerated at step 158, and the system may await the operator to initiatea further color/optical measurement.

[0151] With unique audio tones presented to an operator in accordancewith the particular operating state of the system, the operator's use ofthe system may be greatly facilitated. Such audio information also tendsto increase operator satisfaction and skill level, as, for example,acceptance tones provide positive and encouraging feedback when thesystem is operated in a desired manner.

[0152] The color/optical measuring systems and methods in accordancewith the present invention may be applied to particular advantage in thefield of dentistry, as will be more fully explained hereinafter. Inparticular the present invention includes the use of such systems andmethods to measure the color and other attributes of a tooth in order toprepare a dental prosthesis or intraoral tooth-colored fillings, or toselect denture teeth or to determine a suitable cement color forporcelain/resin prostheses. The present invention also provides methodsfor storing and organizing measured data such as in the form of apatient database.

[0153]FIG. 16A is a flow chart illustrating a general dental applicationprocess flow for use of the color/optical measuring systems and methodsin accordance with the present invention. At step 200, the color/opticalmeasuring system may be powered-up and stabilized, with any requiredinitialization or other setup routines performed. At step 200, anindication of the system status may be provided to the operator, such asthrough LCD 14 or speaker 16 of FIG. 1. Also at step 200, the probe tipmay be shielded or a clean probe tip may be inserted in order to reducethe likelihood of contamination (see, e.g. FIGS. 7A to 8B and relateddescription). In other embodiments, a plastic or other shield may alsobe used (which may be disposable, cleanable/reusable, etc., aspreviously described), so long as it is constructed and/or positioned soas to not adversely affect the measurement process.

[0154] At step 202, the patient and the tooth to be measured areprepared. Any required cleaning or other tooth preparation would beperformed at step 202. Any required patient consultation about the typeof prosthesis or area of a tooth to be matched would be performed at (orbefore) step 202. In certain embodiments, a positioning device isprepared at step 202, such as is illustrated in FIGS. 17A and 17B. Insuch embodiments, for example, a black or other suitably-coloredmaterial 282, which may adhere to tooth 280 (such as with a suitableadhesive), is formed to have opening 281 larger than the diameter of themeasuring probe, with opening 281 centered on the area of tooth 280 tobe measured. The material of positioning device 282 is formed in amanner to fit on/over tooth 280 (such as over the incisal edge of tooth280 and/or over one or more adjacent teeth) so that it may be placedon/over tooth 280 in a repeatable manner. Such a positioning device mayserve to ensure that the desired area of tooth 280 is measured, and alsoallows for repeat measurements of the same area for purposes ofconfirmation, fluorescence measurement, or other optical measurement, orthe like. Any other pre-measurement activities may be performed at (orbefore) step 202.

[0155] At step 204, the operator (typically a dentist or other dentalprofessional) moves the probe towards the area of the tooth to bemeasured. This process preferably is conducted in accordance with themethodology described with reference to FIGS. 5A, 5B and 6, andpreferably is accompanied by audio tones such as described withreference to FIG. 15. With the present invention, the operator mayobtain color and translucency data, etc., for example, from a desiredarea of the tooth to be measured. During step 204, an acceptedcolor/optical measurement is made, or some indication is given to theoperator that the measurement step needs to be repeated or some otheraction taken. After an accepted color/optical measurement is made atstep 204, for example, the dentist may operate on the desired tooth orteeth or take other action. Before or after such action, additionalmeasurements may be taken as needed (see, e.g., FIG. 18 and relateddescription).

[0156] Upon successful completion of one or more measurements taken atstep 204, the process proceeds to step 206. At step 206, any dataconversion or processing of data collected at step 204 may be performed.For example, in the embodiment of FIG. 1, detailed color spectrum andtranslucency information may be generated. In a particular dentalapplication, however, it may be that a dental lab, for example, requiresthat the color be presented in Munsell format (i.e., chroma, hue andvalue), RGB values, XYZ coordinates, CIELAB values, Hunter values, orsome other color data format. With the spectral/color informationproduced by the present invention, data may be converted to such formatsthrough conventional math, for example. Such math may be performed bymicroprocessor 10 or computer 13A of FIG. 1, or in some other manner. Italso should be noted that, in certain embodiments, the data produced atstep 204 in accordance with the present invention may be used directlywithout data conversion. In such embodiments, step 206 may be omitted.In other embodiments, step 206 consists of data formatting, such aspreparing the data for reproduction in hard copy, pictorial or otherform, or for transmission as facsimile or modem data. Finally, incertain embodiments a translucency factor is computed in a formatsuitable for the particular application. In yet other embodiments, asurface texture or detail factor is computed in a format suitable forthe particular application. In yet other embodiments, a surface glossfactor is computed in a format suitable for the particular application.

[0157] At step 208, a matching is optionally attempted between the dataproduced at steps 204 and 206 (if performed) and a desired color (inother embodiments, the process may proceed from 204 directly to 210, oralternatively steps 206 and 208 may be combined). For example, a numberof “shade guides” are available in the market, some of which are knownin the industry as Vita shade guides, Bioform shade guides or othercolor matching standards, guides or references or custom shade guides.In certain preferred embodiments, a lookup table is prepared and loadedinto memory (such as memory associated with microprocessor 10 orcomputer 13A of FIG. 1), and an attempt is made to the closest match ormatches of the collected data with the known shade guides, custom shadeguides or reference values. In certain embodiments, a translucencyfactor and/or gloss factor and/or a surface texture or detail factoralso is used in an effort to select the best possible match.

[0158] In a particular aspect of certain embodiments of the presentinvention, at step 208 a material correlation lookup table is accessed.Based on the color and translucency data obtained at step 204, aproposed recipe of materials, pigments or other instruction informationis prepared for a prosthesis or filling, etc., of the desired color andtranslucency, etc. With the detailed color and other information madeavailable in accordance with the present invention, a direct correlationwith the relevant constituent materials may be made. In still otherembodiments, such information is made available to an automated mixingor manufacturing machine for preparation of prosthesis or material ofthe desired color and translucency, etc., as more fully describedelsewhere herein.

[0159] At step 210, based on the results of the preceding steps, theprosthesis, denture, intraoral tooth-colored filling material or otheritems are prepared. This step may be performed at a dental lab, or, incertain embodiments, at or near the dental operatory. For remotepreparation, relevant data produced at steps 204, 206 and/or 208 may besent to the remote lab or facility by hardcopy, facsimile or modem orother transmission. What should be understood from the foregoing isthat, based on data collected at step 204, a prosthesis may be preparedof a desirable color and/or other optical characteristic at step 210.

[0160] At step 212, the prosthesis or other material prepared at step210 may be measured for confirmation purposes, again preferablyconducted in accordance with the methodology described with reference toFIGS. 5A, 5B and 6, and preferably accompanied by audio tones such asdescribed with reference to FIG. 15. A re-measure of the tooth in thepatient's mouth, etc. also may be made at this step for confirmationpurposes. If the confirmation process gives satisfactory results, theprosthesis, denture, composite filling or other material may bepreliminarily installed or applied in the patient at step 214. At step216, a re-measure of the prosthesis, denture, composite filling or othermaterials optionally may be made. If the results of step 216 areacceptable, then the prosthesis may be more permanently installed orapplied in the patient at step 218. If the results of step 216 are notacceptable, the prosthesis may be modified and/or other of the stepsrepeated as necessary in the particular situation.

[0161] With reference to FIG. 16B, a further embodiment of the presentinvention will be explained. With this embodiment, an instrument andmethod such as previously described may be advantageously utilized toprepare a tooth to receive a prosthesis.

[0162] A dental prosthesis such as a crown or a laminate has opticalproperties that are determined by a number of factors. Determiningfactors include the material of the prosthesis, along with the cementutilized to bond the prosthesis to the tooth and the underlying opticalproperties of the tooth itself. For example, in the preparation of atooth for a laminate, the thickness of the laminate combined with thebonding cement and the color of the underlying prepared tooth allcontribute to the final optical properties of the prosthesis. In orderto prepare an optimum prosthesis such as from an esthetic standpoint,the dentist may need to prepare the tooth for the laminate by removingmaterial from the tooth. The final desired esthetic color, shape andcontours of the tooth determines the amount of material needed to beremoved from the tooth, which determines the final thickness of thelaminate, and in significant part may determine whether or not the finalrestoration will have a desired and esthetically pleasing result ascompared to neighboring teeth. By measuring the color of the neighboringteeth, and by measuring the color of the underlying tooth being preparedfor the laminate, the amount of tooth material to be removed, or therange of material that should be removed, may be determined and reportedto the dentist as the tooth is being prepared.

[0163] At step 201, the process is commenced. Any initial calibration orother preparatory steps may be undertaken. At step 203, the dentist maymeasure the optical properties including color of one or moreneighboring teeth. At step 205, the dentist may measure the opticalproperties including color of the tooth receiving the prosthesis. Atstep 207, a first amount of material to be removed is calculated orestimated (such as by microprocessor 10, computer 13A or other suitablecomputing device). The first amount is determined based on known colorproperties of the available laminates, the estimated thickness of thelaminate, and the color of the tooth to receive the laminate. If, forexample, the tooth to receive the laminate is dark to the degree that anesthetically pleasing laminate likely cannot be produced (based on therange of color/optical characteristics of the known availablelaminates), then an estimate is made of how much material should beremoved such that a thicker laminate will result in a desired andesthetically pleasing result. At step 209 the dentist removes the firstamount of material (or approximately such amount) from the tooth (usingknown removal techniques, etc.). At step 211, the dentist may againmeasure the optical properties including color of the tooth receivingthe prosthesis. At step 213, a calculation or estimation is made (in amanner analogous to step 207) of whether additional material should beremoved, and, if so, how much. At step 215, if needed, additionalmaterial is removed, with steps 211, 213 and 215 repeated as necessary.In preferred embodiments, based on known/measured/empirical dataanalysis of color/optical properties of teeth, at steps such as steps205 and 211, a comparison or assessment may be made of whether the toothbeing prepared is getting too near the pulp (such as by detection of apink color, for example). Based on such threshold or other typecriteria, the dentist may be alerted that further material should not beremoved in order to minimize exposure of the pulp and damage of thetooth. At step 217, if it is determined at step 213 that a desirable andesthetically pleasing laminate may be produced, such laminatepreparation steps are conducted.

[0164] Similar steps could be taken in other industrial endeavors, suchas painting or other finishes, etc.

[0165] In another particular aspect of the present invention, forexample, data processing such as illustrated in FIG. 18 may be taken inconjunction with the processes of FIGS. 16A and/or 16B. At step 286,client database software is run on a computing device, such as computer13A of FIG. 1. Such software may include data records for each patient,including fields storing the history of dental services performed on thepatient, information regarding the status or conditions of the patient'steeth, billing, address and other information. Such software may enter amode by which it is in condition to accept color or other data taken inaccordance with the present invention.

[0166] At step 288, for example, the dentist or other dentalprofessional may select parameters for a particular tooth of the patientto be measured. Depending on the size and condition of the tooth (suchas color gradient or the like), the dentist may sector the tooth intoone or more regions, such as a grid. Thus, for example, in the case oftooth for which it is decided to take four measurements, the tooth maybe sectored into four regions. Such parameters, which may include apictorial representation on the computer of the tooth sectored into fourregions (such as by grid lines), along with tooth identification andpatient information may be entered into the computer at this time.

[0167] At step 290, one or more measurements of the tooth may be taken,such as with a system and method as described in connection with FIGS.1, 5A, 5B and/or 6. The number of such measurements preferably isassociated with the parameters entered at step 288. Thereafter, at step292, the data collected from the measurement(s) may be sent to thecomputer for subsequent processing. As an illustrative example, fourcolor/optical measurements may be taken (for the four regions of thetooth in the above example) and sent to the computer, with the data forthe four color/optical measurements (such as RGB or other values)associated with the four regions in accordance with the enteredparameters. Also, as an example, the displayed pictorial representationof the tooth may have overlaid thereof data indicative of thecolor/optical measurement(s). At step 294, such as after completion ofcolor/optical measurements on the particular patient, the data collectedduring the process may be associatively stored as a part of thepatient's dental records in the data base. In embodiments accompanied byuse of an intraoral camera, for example (see, e.g., FIG. 19 and relateddescription), captured images of one or more of the patient's teeth alsomay be associatively stored as part of the patient's dental records. Incertain embodiments, a picture captured by the intraoral camera isoverlaid with grid or sector lines (such as may be defined in step 288),with color or other data measured as described herein also overlaid overthe captured image. In such a manner, the color or other data may beelectronically and visually associated with a picture of the particularmeasured tooth, thereby facilitating the use of the system and theunderstanding of the collected data. In still other embodiments, allsuch captured image and color measurement records include a time and/ordate, so that a record of the particular history of a particular toothof a particular patient may be maintained. See FIGS. 24 to 26 and 32 to34 and related description for additional embodiments utilizing anintraoral camera, etc., in accordance with the present invention.

[0168] In yet another particular aspect of the present invention, ameasuring device and method (such as described elsewhere herein) may becombined with an intraoral camera and other implements. As illustratedin FIG. 19, control unit 300 contains conventional electronics andcircuitry, such as power supplies, control electronics, light sourcesand the like. Coupled to control unit 300 is intraoral camera 301 (forviewing, and capturing images of, a patient's tooth or mouth, etc.),curing light 302 (such as for curing light-cured intraoral fillingmaterial), measuring device 304 (such as described elsewhere herein),and visible light 306 (which may be an auxiliary light for intraoralexaminations and the like). With such embodiments, color, translucencyfluorescence, gloss, surface texture and/or other data collected for aparticular tooth from measuring device 304 may be combined with imagescaptured by intraoral camera 301, with the overall examination andprocessing of the patient facilitated by having measuring device 304,intraoral camera 301, curing light 302 and visible light 306 integratedinto a single unit. Such integration serves to provide synergisticbenefits in the use of the instruments, while also reducing costs andsaving physical space. In another particular aspect of such embodiments,the light source for measuring device 304 and intraoral camera 301 areshared, thereby resulting in additional benefits.

[0169] Further embodiments of the present invention will now bedescribed with reference to FIGS. 20 to 23. The previously describedembodiments generally rely on movement of the probe with respect to theobject/tooth being measured. While such embodiments provide greatutility in many applications, in certain applications, such as robotics,industrial control, automated manufacturing, etc. (such as positioningthe object and/or the probe to be in proximity to each other, detectingcolor/optical properties of the object, and then directing the object,e.g., sorting, based on the detected color/optical properties, forfurther industrial processing, packaging, etc.) it may be desired tohave the measurement made with the probe held or positionedsubstantially stationary above the surface of the object to be measured(in such embodiments, the positioned probe may not be handheld as withcertain other embodiments). Such embodiments also may have applicabilityin the field of dentistry (in such applications, “object” generallyrefers to a tooth, etc.).

[0170]FIG. 20 illustrates such a further embodiment. The probe of thisembodiment includes a plurality of perimeter sensors and a plurality ofcolor sensors coupled to receivers 312-320. The color sensors andrelated components, etc., may be constructed to operate in a manneranalogous to previously described embodiments. For example, fiber opticcables or the like may couple light from source 310 that is received byreceivers 312-320 to sharp cut-off filters or to notch filters, with thereceived light measured over precisely defined wavelengths (see, e.g.,FIGS. 1, 3 and 11-14 and related description). Color/opticalcharacteristics of the object may be determined from the plurality ofcolor sensor measurements, which may include three such sensors in thecase of a tristimulus instrument, or 8, 12, 15 or more color sensors fora more full bandwidth system (the precise number may be determined bythe desired color resolution, etc.).

[0171] With this embodiment, a relatively greater number of perimetersensors are utilized (as opposed, for example, to the three perimetersensors used in certain preferred embodiments of the present invention).As illustrated in FIG. 20, a plurality of triads of receivers 312-320coupled to perimeter sensors are utilized, where each triad in thepreferred implementation consists of three fiber optics positioned equaldistance from light source 310, which in the preferred embodiment is acentral light source fiber optic. The triads of perimeterreceivers/sensors may be configured as concentric rings of sensorsaround the central light source fiber optic. In FIG. 20, ten such triadrings are illustrated, although in other embodiments a lesser or greaternumber of triad rings may be utilized, depending upon the desiredaccuracy and range of operation, as well as cost considerations and thelike.

[0172] The probe illustrated in FIG. 20 may operate within a range ofheights (i.e., distances from the object being measured). As withearlier embodiments, such height characteristics are determinedprimarily by the geometry and constituent materials of the probe, withthe spacing of the minimal ring of perimeter sensors determining theminimal height, and the spacing of the maximal ring of perimeter sensorsdetermining the maximum height, etc. It therefore is possible toconstruct probes of various height ranges and accuracy, etc., by varyingthe number of perimeter sensor rings and the range of ring distancesfrom the central source fiber optic. It should be noted that suchembodiments may be particularly suitable when measuring similar types ofmaterials, etc.

[0173] As described earlier, the light receiver elements for theplurality of receivers/perimeter sensors may be individual elements suchas Texas Instruments TSL230 light-to-frequency converters, or may beconstructed with rectangular array elements or the like such as may befound in a CCD camera. Other broadband-type of light measuring elementsare utilized in other embodiments. Given the large number of perimetersensors used in such embodiments (such as 30 for the embodiment of FIG.16), an array such as CCD camera-type sensing elements may be desirable.It should be noted that the absolute intensity levels of light measuredby the perimeter sensors is not as critical to such embodiments of thepresent invention; in such embodiments differences between the triads ofperimeter light sensors are advantageously utilized in order to obtainoptical measurements.

[0174] Optical measurements may be made with such a probe byholding/positioning the probe near the surface of the object beingmeasured (i.e., within the range of acceptable heights of the particularprobe). The light source providing light to light source 310 is turnedon and the reflected light received by receivers 312-320 (coupled to theperimeter sensors) is measured. The light intensity of the rings oftriad sensors is compared. Generally, if the probe is perpendicular tothe surface and if the surface is flat, the light intensity of the threesensors of each triad should be approximately will be equal. If theprobe is not perpendicular to the surface or if the surface is not flat,the light intensity of the three sensors within a triad will not beequal. It is thus possible to determine if the probe is perpendicular tothe surface being measured, etc. It also is possible to compensate fornon-perpendicular surfaces by mathematically adjusting the lightintensity measurements of the color sensors with the variance inmeasurements of the triads of perimeters sensors.

[0175] Since the three sensors forming triads of sensors are atdifferent distances (radii) from central light source 310, it isexpected that the light intensities measured by light receivers 312-320and the perimeter sensors will vary. For any given triad of sensors, asthe probe is moved closer to the surface, the received light intensitywill increase to a maximum and then sharply decrease as the probe is,moved closer to the surface. As with previously-described embodiments,the intensity decreases rapidly as the probe is moved less than thepeaking height and decreases rapidly to zero or almost zero for opaqueobjects. The value of the peaking height depends principally upon thedistance of the particular receiver from light source 310. Thus, thetriads of sensors will peak at different peaking heights. By analyzingthe variation in light values received by the triads of sensors, theheight of the probe can be determined. Again, this is particularly truewhen measuring similar types of materials. As discussed earlier,comparisons with previously-stored data also may be utilized to madesuch determinations or assessments, etc.

[0176] The system initially is calibrated against a neutral background(e.g., a gray background), and the calibration values are stored innon-volatile memory (see, e.g., processor 10 of FIG. 1). For any givencolor or intensity, the intensity for the receivers/perimeter sensors(independent of distance from the central source fiber optic) in generalshould vary equally. Hence, a white surface should produce the highestintensities for the perimeter sensors, and a black surface will producethe lowest intensities. Although the color of the surface will affectthe measured light intensities of the perimeter sensors, it shouldaffect them substantially equally. The height of the probe from thesurface of the object, however, will affect the triads of sensorsdifferently. At the minimal height range of the probe, the triad ofsensors in the smallest ring (those closest to the source fiber optic)will be at or about their maximal value. The rest of the rings of triadswill be measuring light at intensities lower than their maximal values.As the probe is raised/positioned from the minimal height, the intensityof the smallest ring of sensors will decrease and the intensity of thenext ring of sensors will increase to a maximal value and will thendecrease in intensity as the probe is raised/positioned still further.Similarly for the third ring, fourth ring and so on. Thus, the patternof intensities measured by the rings of triads will be height dependent.In such embodiments, characteristics of this pattern may be measured andstored in non-volatile RAM look-up tables (or the like) for the probe bycalibrating it in a fixture using a neutral color surface. Again, theactual intensity of light is not as important in such embodiments, butthe degree of variance from one ring of perimeter sensors to another is.

[0177] To determine a measure of the height of the probe from thesurface being measured, the intensities of the perimeter sensors(coupled to receivers 312-320) is measured. The variance in lightintensity from the inner ring of perimeter sensors to the next ring andso on is analyzed and compared to the values in the look-up table todetermine the height of the probe. The determined height of the probewith respect to the surface thus may be utilized by the system processorto compensate for the light intensities measured by the color sensors inorder to obtain reflectivity readings that are in general independent ofheight. As with previously described embodiments, the reflectivitymeasurements may then be used to determine optical characteristics ofthe object being measured, etc.

[0178] It should be noted that audio tones, such as previouslydescribed, may be advantageously employed when such an embodiment isused in a handheld configuration. For example, audio tones of varyingpulses, frequencies and/or intensities may be employed to indicate theoperational status of the instrument, when the instrument is positionedwithin an acceptable range for color measurements, when valid or invalidcolor measurements have been taken, etc. In general, audio tones aspreviously described may be adapted for advantageous use with suchfurther embodiments.

[0179]FIG. 21 illustrates a further such embodiment of the presentinvention. The preferred implementation of this embodiment consists of acentral light source 310 (which in the preferred implementation is acentral tight source fiber optic), surrounded by a plurality of lightreceivers 322 (which in the preferred implementation consists of threeperimeter light receiver fiber optics). The three perimeter lightreceiver fiber optics, as with earlier described embodiments, may beeach spliced into additional fiber optics that pass to light intensityreceivers/sensors, which may be implemented with Texas InstrumentsTSL230 light to frequency converters as described previously. One fiberof each perimeter receiver is coupled to a sensor and measured full bandwidth (or over substantially the same bandwidth) such as via a neutraldensity filter, and other of the fibers of the perimeter receivers arecoupled to sensors so that the light passes through sharp cut off ornotch filters to measure the light intensity over distinct frequencyranges of light (again, as with earlier described embodiments). Thus,there are color light sensors and neutral “perimeter” sensors as withpreviously described embodiments. The color sensors are utilized todetermine the color or other optical characteristics of the object, andthe perimeter sensors are utilized to determine if the probe isperpendicular to the surface and/or are utilized to compensate fornon-perpendicular angles within certain angular ranges.

[0180] In the embodiment of FIG. 21, the angle of the perimeter sensorfiber optics is mechanically varied with respect to the central sourcefiber optic. The angle of the perimeter receivers/sensors with respectto the central source fiber optic is measured and utilized as describedhereinafter. An exemplary mechanical mechanism, the details of which arenot critical so long as desired, control movement of the perimeterreceivers with respect to the light source is obtained, is describedwith reference to FIG. 22.

[0181] The probe is held within the useful range of the instrument(determined by the particular configuration and construction, etc.), anda color measurement is initiated. The angle of the perimeterreceivers/sensors with respect to the central light source is variedfrom parallel to pointing towards the central source fiber optic. Whilethe angle is being varied, the intensities of the light sensors for theperimeter sensors (e.g., neutral sensors) and the color sensors ismeasured and saved along with the angle of the sensors at the time ofthe light measurement. The light intensities are measured over a rangeof angles. As the angle is increased the light intensity will increaseto a maximum value and will then decrease as the angle is furtherincreased. The angle where the light values is a maximum is utilized todetermine the height of the probe from the surface. As will be apparentto those skilled in the art based on the teachings provided herein, withsuitable calibration data, simple geometry or other math, etc., may beutilized to calculate the height based on the data measured duringvariation of the angle. The height measurement may then be utilized tocompensate for the intensity of the color/optical measurements and/orutilized to normalize color values, etc.

[0182]FIG. 22 illustrates an exemplary embodiment of a mechanicalarrangement to adjust and measure the angle of the perimeter sensors.Each perimeter receiver/sensor 322 is mounted with pivot arm 326 onprobe frame 328. Pivot arm 326 engages central ring 332 in a manner toform a cam mechanism. Central ring 332 includes a groove that holds aportion of pivot arm 326 to form the cam mechanism. Central ring 332 maybe moved perpendicular with respect to probe frame 328 via linearactuator 324 and threaded spindle 330. The position of central ring 332with respect to linear actuator 324 determines the angle of perimeterreceivers/sensors 322 with respect to light source 310. Such angularposition data vis-à-vis the position of linear actuator 324 may becalibrated in advance and stored in non-volatile memory, and later usedto produce color/optical characteristic measurement data as previouslydescribed.

[0183] Referring pow to FIG. 24, a further embodiment of the presentinvention will be explained.

[0184] Intraoral reflectometer 380, which may be constructed asdescribed above, includes probe 381. Data output from reflectometer 380is coupled to computer 384 over bus 390 (which may be a standard serialor parallel bus, etc.). Computer 384 includes a video freeze framecapability and preferably a modem. Intraoral camera 382 includeshandpiece 383 and couples video data to computer 384 over bus 392.Computer 384 is coupled to remote computer 386 over telecommunicationchannel 388, which may be a standard telephone line, ISDN line, a LAN orWAN connection, etc. With such an embodiment, video measurements may betaken of one or more teeth by intraoral camera 382, along with opticalmeasurements taken by intraoral reflectometer 380. Computer 384 maystore still picture images taken from the output of intraoral camera382.

[0185] Teeth are known to have variations in color from tooth to tooth,and teeth are known to have variations in color over the area of onetooth. Intraoral cameras are known to be useful for showing the detailsof teeth. Intraoral cameras, however, in general have poor colorreproducibility. This is due to variations in the camera sensingelements (from camera to camera and over time etc.), in computermonitors, printers, etc. As a result of such variations, it presently isnot possible to accurately quantify the color of a tooth with anintraoral camera. With the present embodiment, measuring and quantifyingthe color or other optical properties of teeth may be simplified throughthe use of an intraoral reflectometer in accordance with the presentinvention, along with an intraoral camera.

[0186] In accordance with this embodiment, the dentist may capture astill picture of a tooth and its adjacent teeth using the freeze framefeature of computer 384. Computer 384, under appropriate software andoperator control, may then “postureize” the image of the tooth and itsadjacent teeth, such as by limiting the number of gray levels of theluminance signal, which can result in a color image that shows contoursof adjacent color boundaries. As illustrated in FIG. 25, such apostureization process may result in teeth 396 being divided intoregions 398, which follow color contours of teeth 396. As illustrated,in general the boundaries will be irregular in shape and follow thevarious color variations found on particular teeth.

[0187] With teeth postureized as illustrated in FIG. 25, computer 384may then highlight (such as with a colored border, shading, highlight orthe like) a particular color region on a tooth to be measured, and thenthe dentist may then measure the highlighted region with intraoralreflectometer 380. The output of intraoral reflectometer 380 is input tocomputer 384 over bus 390, and computer 384 may store in memory or on ahard disk or other storage medium the color/optical data associated withthe highlighted region. Computer 384 may then highlight another regionand continue the process until color/optical data associated with alldesired highlighted regions have been stored in computer 384. Suchcolor/optical data may then be stored in a suitable data base, alongwith the video image and posturized video image of the particular teeth,etc.

[0188] Computer 384 may then assess if the measured value of aparticular color region is consistent with color measurements foradjacent color regions. If, for example, a color/optical measurement forone region indicates a darker region as compared to an adjacent region,but the postureized image indicates that the reverse should be true,then computer 384 may notify the dentist (such as with an audio tone)that one or more regions should be remeasured with intraoralreflectometer 380. Computer 384 may make such relative colordeterminations (even though the color values stored in computer 384 fromthe freeze frame process are not true color values) because thevariations from region to region should follow the same pattern as thecolor/optical measurements taken by intraoral reflectometer 380. Thus,if one region is darker than its neighbors, then computer 384 willexpect that the color measurement data from intraoral reflectometer 380for the one region also will be darker relative to color measurementdata for the neighboring regions, etc.

[0189] As with the optical characteristics measurement data and capturedimages discussed previously, the postureized image of the teeth, alongwith the color/optical measurement data for the various regions of theteeth, may be conveniently stored, maintained and accessed as part ofthe patient dental records. Such stored data may be utilizedadvantageously in creating dental prosthesis that more correctly matchthe colors/regions of adjacent teeth. Additionally, in certainembodiments, such data images are used in conjunction with smileanalysis software to further aid in the prosthesis preparation.

[0190] In a further refinement to the foregoing embodiment, computer 384preferably has included therein, or coupled thereto, a modem. With sucha modem capability (which may be hardware or software), computer 384 maycouple data to remote computer 386 over telecommunication channel 388.For example, remote computer 386 may be located at a dental laboratoryremotely located. Video images captured using intraoral camera 382 andcolor/optical data collected using intraoral reflectometer may betransmitted to a dental technician (for example) at the remote location,who may use such images and data to construct dental prosthesis.Additionally, computer 384 and remote computer 386 may be equipped withan internal or external video teleconference capability, therebyenabling a dentist and a dental technician or ceramist, etc., to have alive video or audio teleconference while viewing such images and/ordata.

[0191] For example, a live teleconference could take place, whereby thedental technician or ceramist views video images captured, usingintraoral camera 383, and after viewing images of the patient's teethand facial features and complexion, etc., instruct the dentist as towhich areas of the patient's teeth are recommended for measurement usingintraoral reflectometer 380. Such interaction between the dentist anddental technician or ceramist may occur with or without postureizationas previously described. Such interaction may be especially desirableat, for example, a try-in phase of a dental prosthesis, when minorchanges or subtle characterizations may be needed in order to modify theprosthesis for optimum esthetic results.

[0192] A still further refinement may be understood with reference toFIG. 26. As illustrated in FIG. 26, color calibration chart 404 could beutilized in combination with various elements of the previouslydescribed embodiments, including intraoral camera 382. Color calibrationchart 404 may provide a chart of known color values, which may beemployed, for example, in the video image to further enhance correctskin tones of patient 402 in the displayed video image. As the patient'sgingival tissue, complexion and facial features, etc., may influence thefinal esthetic results of a dental prosthesis, such a color calibrationchart may be desirably utilized to provide better esthetic results.

[0193] As an additional example, such a color calibration chart may beutilized by computer 384 and/or 386 to “calibrate” the color data withina captured image to true or known color values. For example, colorcalibration chart 404 may include one or more orientation markings 406,which may enable computers 384 and/or 386 to find and position colorcalibration chart 404 within a video frame. Thereafter, computers 384and/or 386 may then compare “known” color data values from colorcalibration chart (data indicative of the colors within colorcalibration chart 404 and their position relative to orientation mark ormarkings 406 are stored within computers 384 and/or 386, such as in alookup table, etc.) with the colors captured within the video image atpositions corresponding to the various colors of color calibration chart404. Based on such comparisons, computers 384 and/or 386 may color,adjust the video image in order to bring about a closer correspondencebetween the colors of the video image and known or true colors fromcolor calibration chart 404.

[0194] In certain embodiments, such color adjusted video data may beused in the prosthesis preparation process, such as to color adjust thevideo image (whether or not postureized) in conjunction withcolor/optical data collected using intraoral reflectometer 380 (forexample, as described above or using data from intraoral reflectometer380 to further color adjust portions of the video image), or to addsubtle characterizations or modifications to a dental prosthesis, or toeven prepare a dental prosthesis, etc. While not believed to be asaccurate, etc. as color/optical data collected using intraoralreflectometer 380, such color adjusted video data may be adequate incertain applications, environments, situations, etc., and such coloradjusted video data may be utilized in a similar manner to color datataken by a device such as intraoral reflectometer 380, including, forexample, prosthesis preparation, patient data collection and storage,materials preparation, such as described elsewhere herein.

[0195] It should be further noted that color calibration chart 404 maybe specifically adapted (size, form and constituent materials, etc.) tobe positioned inside of the patient's mouth to be placed near the toothor teeth being examined, so as to be subject to the same or nearly thesame ambient lighting and environmental conditions, etc., as is thetooth or teeth being examined. It also should further be noted that theutilization of color calibration chart 404 to color correct video imagedata with a computer as provided herein also may be adapted to be usedin other fields, such as medical, industrial, etc., although its noveland advantageous use in the field of dentistry as described herein is ofparticular note and emphasis herein.

[0196]FIG. 27 illustrates a further embodiment of the present invention,in which an intraoral reflectometer in accordance with the presentinvention may be adapted to be mounted on, or removably affixed to, adental chair. An exemplary dental chair arrangement in accordance withthe present invention includes dental chair 410 is mounted on base 412,and may include typical accompaniments for such chairs, such as footcontrol 414, hose(s) 416 (for suction or water, etc.), cuspidor andwater supply 420 and light 418. A preferably movable arm 422 extends outfrom support 428 in order to provide a conveniently locatable support430 on which various dental instruments 424 are mounted or affixed in aremovable manner. Bracket table 426 also may be included, on which adentist may position other instruments or materials. In accordance withthis embodiment, however, instruments 424 include an intraoral,reflectometer in accordance with the present invention, which isconveniently positioned and removably mounted/affixed on support 430, sothat color/optical measurements, data collection and storage andprosthesis preparation may be conveniently carried out by the dentist.As opposed to large and bulky prior art instruments, the presentinvention enables an intraoral reflectometer for collectingcolor/optical data, in some embodiments combined or utilized with anintraoral camera as described elsewhere herein, which may be readilyadapted to be positioned in a convenient location on a dental chair.Such a dental chair also may be readily adapted to hold otherinstruments, such as intraoral cameras, combined intraoralcamera/reflectors, drills, lights, etc.

[0197] With the foregoing as background, various additional preferredembodiments utilizing variable aperture receivers in order to measure,for example, the degree of gloss of the surface will now be describedwith references to FIGS. 28A to 30B. Various of the electronics andspectrophotometer/reflectometer implements described above will beapplicable to such preferred embodiments.

[0198] Referring to FIG. 28A, a probe utilizing variable aperturereceivers will now be described. In FIG. 28A, source A 452 represents asource fiber optic of a small numerical aperture NA, 0.25 for example;receivers B 454 represent receiver fiber optics of a wider numericalaperture, 0.5 for example; receivers C 456 represent receiver fiberoptics of the same numerical aperture as source A but is shown with asmaller core diameter; and receivers D 458 represent receiver fiberoptics of a wider numerical aperture, 0.5 for example.

[0199] One or more of receiver(s) B 454 (in certain embodiments onereceive a be utilized, while in other embodiments a plurality ofreceivers B are utilized, which may be circularly arranged around sourceA, such as 6 or 8 such receivers B) pass to a spectrometer (see, e.g.,FIGS. 1, 3, 11, 12, configured as appropriate for such preferredembodiments). Receiver(s) B 454 are used to measure the spectrum of thereflected light. Receivers C 456 and D 458 pass to broad band(wavelength) optical receivers and are used to correct the measurementmade by receiver(s) B. Receivers C 456 and D 458 are used to correct forand to detect whether or not the probe is perpendicular to the surfaceand to measure/assess the degree of specular versus diffuse reflection(the coefficient of specular reflection, etc.) and to measure thetranslucency of the material/object.

[0200]FIG. 28B illustrates a refinement of the embodiment of FIG. 28A,in which receivers B 454 are replaced by a cylindrical arrangement ofclosely packed, fine optical fibers 454A, which generally surround lightsource 452 as illustrated. The fibers forming the cylindricalarrangement for receivers B 454, are divided into smaller groups offibers and are presented, for example, to light sensors 8 shown inFIG. 1. The number of groups of fibers is determined by the number oflight sensors. Alternately, the entire bundle of receiver fibers B 454is presented to a spectrometer such as a diffraction gratingspectrometer of conventional design. As previously described, receiversC 456 and D 458 may be arranged on the periphery thereof. In certainembodiments, receivers C and D may also consist of bundles of closelypacked, fine optical fibers. In other embodiments they consist of singlefiber optics.

[0201] The assessment of translucency in accordance with embodiments ofthe present invention have already been described. It should be noted,however, that in accordance with the preferred embodiment both the lightreflected from the surface of the material/object (i.e., the peakingintensity) and its associated spectrum and the spectrum of the lightwhen it is in contact with the surface of the material/object may bemeasured/assessed. The two spectrums typically will differ in amplitude(the intensity or luminance typically will be greater above the surfacethan in contact with the surface) and the spectrums for certainmaterials may differ in chrominance (i.e., the structure of thespectrum) as well.

[0202] When a probe in accordance with such embodiments measures thepeaking intensity, it in general is measuring both the light reflectedfrom the surface and light that penetrates the surface, gets bulkscattered within the material and re-emerges from the material (e.g.,the result of translucency). When the probe, is in contact with thesurface (e.g., less than the critical height), no light reflecting fromthe surface can be detected by the receiver fiber optics, and thus anylight detected by the receivers is a result of the translucency of thematerial and its spectrum is the result of scattering within the bulk ofthe material. The “reflected spectrum” and the “bulk spectrum” ingeneral may be different for different materials, and assessments ofsuch reflected and bulk spectrum provide additional parameters formeasuring, assessing and/or characterizing materials, surfaces, objects,teeth, etc., and provide new mechanisms to distinguish translucent andother types of materials.

[0203] In accordance with preferred embodiments of the presentinvention, an assessment or measurement of the degree of gloss (orspecular reflection) may be made. For understanding thereof, referenceis made to FIGS. 29 to 30B.

[0204] Referring to FIG. 29, consider two fiber optics, source fiberoptic 460 and receiver fiber optic 462, arranged perpendicular to aspecular surface as illustrated. The light reflecting from a purelyspecular surface will be reflected in the form of a cone. As long as thenumerical aperture of the receiver fiber optic is greater than or equalto the numerical aperture of the source fiber optic, all the lightreflected from the surface that strikes the receiver fiber optic will bewithin the receiver fiber optic's acceptance cone and will be detected.In general, it does not matter what the numerical aperture of thereceiver fiber optic is, so long as it is greater than or equal to thenumerical aperture of the source fiber optic. When the fiber optic pairis far from the surface, receiver fiber optic 462 is fully illuminated.Eventually, as the pair approaches surface 464, receiver fiber optic 462is only partially illuminated. Eventually, at heights less than or equalto the critical height h_(c) receiver fiber optic 462 will not beilluminated. In general, such as for purely specular surfaces, it shouldbe noted that the critical height is a function of the numericalaperture of source fiber optic 460, and is not a function of thenumerical aperture of the receiver.

[0205] Referring now to FIGS. 30A and 30B, consider two fiber optics(source 460 and receiver 462) perpendicular to diffuse surface 464A asillustrated in FIG. 30A (FIG. 30B depicts mixed specular/diffuse surface464B and area of intersection 466B). Source fiber optic 460 illuminatescircular area 466A on surface 464A, and the light is reflected fromsurface 464A. The light, however, will be reflected at all angles,unlike a specular surface where the light will only be reflected in theform of a cone. Receiver fiber optic 462 in general is alwaysilluminated at all heights, although it can only propagate and detectlight that strikes its surface at an angle less than or equal to itsacceptance angle. Thus, when the fiber optic pair is less than thecritical height, receiver fiber optic 462 detects no light. As theheight increases above the critical height, receiver fiber optic 462starts to detect light that originates from the area of intersection ofthe source and receiver cones as illustrated. Although light may beincident upon receiver fiber optic 462 from other areas of theilluminated circle, it is not detected because it is greater than theacceptance angle of the receiver fiber.

[0206] As the numerical aperture of receiver fiber optic 462 increases,the intensity detected by receiver fiber optic 462 will increase fordiffuse surfaces, unlike a specular surface where the received intensityis not a function of receiver fiber optic numerical aperture. Thus, fora probe constructed with a plurality of receiver fiber optics withdifferent numerical apertures, as in preferred embodiments of thepresent invention, if the surface is a highly glossy surface, bothreceivers (see, e.g., receivers 456 and 458 of FIG. 28A, will measurethe same light intensity. As the surface becomes increasingly diffuse,however receiver D 458 will have a greater intensity than receiver C456. The ratio of the two intensities from receivers C/D is a measureof, or correlates to, the degree of specular reflection of the material,and may be directly or indirectly used to quantify the “glossiness” ofthe surface. Additionally, it should be noted that generally receiver C456 (preferably having the same numerical aperture as source fiber opticA 452) measures principally the specular reflected component. Receiver D458, on the other hand, generally measures both diffuse and specularcomponents. As will be appreciated by those skilled in the art, suchprobes and methods utilizing receivers of different/varying numericalapertures may be advantageously utilized, with or without additionaloptical characteristic determinations as described elsewhere herein, tofurther quantify materials such as teeth or other objects.

[0207] Referring now to FIG. 31A, additional preferred embodiments willbe described. The embodiment of FIG. 31A utilizes very narrow numericalaperture, non-parallel fiber optic receivers 472 and very narrownumerical aperture source fiber optic 470 or utilizes other opticalelements to create collimated or nearly collimated source and receiverelements. Central source fiber optic 470 is a narrow numerical aperturefiber optic and receiver fiber optics 472 as illustrated (preferablymore than two such receivers are utilized in such embodiments) are alsonarrow fiber optics. Other receiver fiber optics may be wide numericalaperture fiber optics (e.g., receivers such as receivers 458 of FIG.28A). As illustrated, receiver fiber optics 472 of such embodiments areat an angle with respect to source fiber optic 470, with the numericalaperture of the receiver fiber optics selected such that, when thereceived intensity peaks as the probe is lowered to the surface, thereceiver fiber optics acceptance cones intersect with the entirecircular area illuminated by the source fiber optic, or at least with asubstantial portion of the area illuminated by the source. Thus, thereceivers generally are measuring the same central spot illuminated bythe source fiber optic.

[0208] A particular aspect of such embodiments is that a specularexcluded probe/measurement technique may be provided. In general, thespectrally reflected light is not incident upon the receiver fiberoptics, and thus the probe is only sensitive to diffuse light. Suchembodiments may be useful for coupling reflected light to a multi-bandspectrometer (such as described previously) or to more wide bandsensors. Additionally, such embodiments may be useful as a part of aprobe/measurement technique utilizing both specular included andspecular excluded sensors. An illustrative arrangement utilizing such anarrangement is shown in FIG. 31B. In FIG. 31B, element 470 may consistof a source fiber optic, or alternatively may consist of all or part ofthe elements shown in cross-section in FIG. 28A or 28B. Stillalternatively, non-parallel receiver fiber optics 472 may be parallelalong their length but have a machined, polished, or other finished orother bent surface on the end thereof in order to exclude all, or asubstantial or significant portion, of the specularly reflected light.In other embodiments, receiver fiber optics 472 may contain opticalelements which exclude specularly reflected light. An additional aspectof embodiments of the present invention is that they may be more fullyintegrated with an intraoral camera.

[0209] Referring now to FIGS. 32 to 34, various of such embodiments willbe described for illustrative purposes. In such embodiments, opticalcharacteristic measurement implements such as previously described maybe more closely integrated with an intraoral camera, including commonchassis 480, common cord or cable 482, and common probe 484. In one suchalternative preferred embodiment camera optics 486 are positionedadjacent to spectrometer optics 488 near the end of probe 484, such asillustrated in FIG. 33. Spectrometer optics 488 may incorporate, forexample, elements of color and other optical characteristics measuringembodiments described elsewhere herein, such as shown in FIGS. 1-3,9-10B, 11-12, 20-21, 28A, 28B and 31A and 31B. In another embodiment,camera optics and lamp/light source 490 is positioned near the end ofprobe 484, around which are positioned a plurality of light receivers492. Camera optics and lamp/light source 490 provide illumination andoptics for the camera sensing element and a light source for makingcolor/optical characteristics in accordance with techniques describedelsewhere herein. It should be noted that light receivers 492 are shownas a single ring for illustrative purposes, although in otherembodiments light receivers such as described elsewhere herein (such asin the above-listed embodiments including multiple rings/groups, etc.)may be utilized in an analogous manner. Principles of such camera opticsgenerally are known in the borescope or endoscopes fields.

[0210] With respect to such embodiments, one instrument may be utilizedfor both intraoral camera uses and for quantifying the opticalproperties of teeth. The intraoral camera may be utilized for showingpatients the general state of the tooth, teeth or other dental health,or for measuring certain properties of teeth or dental structure such assize and esthetics or for color postureization as previously described.The optical characteristic measuring implement may then measure theoptical properties of the teeth such as previously described herein. Incertain embodiments, such as illustrated in FIGS. 33 and 34, aprotective shield is placed over the camera for intraoral use in aconventional manner, and the protective shield is removed and aspecialized tip is inserted into spectrometer optics 488 or over cameraoptics and lamp/light source 490 and light receivers 492 (such tips maybe as discussed in connection with FIGS. 23A-23C, with a suitablesecuring mechanism) for infection control, thereby facilitatingmeasuring and quantifying the optical properties. In other embodiments acommon protective shield (preferably thin and tightly fitted, andoptically transparent, such as are known for intraoral cameras) thatcovers both the camera portion and spectrometer portion are utilized.

[0211] Based on the foregoing embodiments, with which translucency andgloss may be measured or assessed, further aspects of the presentinvention will be described. As previously discussed, when light strikesan object, it may be reflected from the surface, absorbed by the bulk ofthe material, or it may penetrate into the material and either beemitted from the surface or pass entirely through the material (i.e.,the result of translucency). Light reflected from the surface may beeither reflected specularly (i.e., the angle of reflection equals theangle of incidence), or it may be reflected diffusely (i.e., light maybe reflected at any angle). When light is reflected from a specularsurface, the reflected light tends to be concentrated. When it isreflected from a diffuse surface, the light tends to be distributed overan entire solid hemisphere (assuming the surface is planar) (see, e.g.,FIGS. 29-30B). Accordingly, if the receivers of such embodiments measureonly diffusely reflected light, the light spectrum (integrated spectrumor gray scale) will be less than an instrument that measures both thespecular and diffusely reflected light. Instruments that measure boththe specular and diffuse components may be referred to as “specularincluded” instruments, while those that measure only the diffusecomponent may be referred to as “specular excluded.”

[0212] An instrument that can distinguish and quantify the degree ofgloss or the ratio of specular to diffusely reflected light, such aswith embodiments previously described, may be utilized in accordancewith the present invention to correct and/or normalize a measured colorspectrum to that of a standardized surface of the same color, such as apurely diffuse or Lambertian surface. As will be apparent to one ofskill in the art, this may be done, for example, by utilizing the glossmeasurement to reduce the value or luminance of the color spectrum (theoverall intensity of the spectrum) to that of the perfectly diffusematerial.

[0213] A material that is translucent, on the other hand, tends to lowerthe intensity of the color spectrum of light reflected from the surfaceof the material. Thus, when measuring the color of a translucentmaterial, the measured spectrum may appear darker than a similar coloredmaterial that is opaque. With translucency measurements made aspreviously described, such translucency measurements may be used toadjust the measured color spectrum to that of a similar colored materialthat is opaque. As will be understood, in accordance with the presentinvention the measured color spectrum may be adjusted, corrected ornormalized based on such gloss and/or translucency data, with theresulting data utilized, for example, for prosthesis preparation orother industrial utilization as described elsewhere herein.

[0214] Additional aspects of the present invention relating to theoutput of optical properties to a dental laboratory for prosthesispreparation will now be described. There are many methods forquantifying color, including CIELab notation, Munsell notation, shadetab values, etc. Typically, the color of a tooth is reported by adentist to the lab in the form of a shade tab value. The nomenclature ofthe shade tab or its value is an arbitrary number assigned to aparticular standardized shade guide. Dentists typically obtain the shadetabs from shade tab suppliers. The labs utilize the shade tabs values inporcelain recipes to obtain the final color of the dental prosthesis.

[0215] Unfortunately, however, there are variances in the color of shadetabs, and there are variances in the color of batches of dentalprosthesis ceramics or other materials. Thus, there are variances in theceramics/material recipes to obtain a final color of a tooth resultingin a prosthesis that does not match the neighboring teeth.

[0216] In accordance with the present invention, such problems may beaddressed as follows. A dental lab may receive a new batch of ceramicmaterials and produce a test batch of materials covering desired color,translucency and/or gloss range(s). The test materials may then bemeasured, with values assigned to the test materials. The values andassociated color, translucency and gloss and other optical propertiesmay then be saved and stored, including into the dental instruments thatthe lab services (such as by modem download). Thereafter, when a dentistmeasures the optical properties of a patient's tooth, the output valuesfor the optical properties may be reported to the lab in a formula thatis directly related, or more desirably correlated, to the materials thatthe lab will utilize in order to prepare the prosthesis. Additionally,such functionality may enable the use of “virtual shade guides” or otherdata for customizing or configuring the instrument for the particularapplication.

[0217] Still other aspects of the present invention will be describedwith reference to FIGS. 35 and 36, which illustrate a cordlessembodiment of the present invention. Cordless unit 500 includes ahousing on which is mounted display 502 for display of color/opticalproperty data or status or other information. Keypad 504 is provided toinput various commands or information. Unit 500 also may be providedwith control switch 510 for initiating measurements or the like, alongwith speaker 512 for audio feedback (such as previously described),wireless infrared serial transceiver for wireless data transmission suchas to an intelligent charging stand (as hereinafter described) and/or toa host computer or the like, battery compartment 516, serial port socket518 (for conventional serial communications to an intelligent chargingstand and/or host computer, and/or battery recharging port 520. Unit 500includes probe 506, which in preferred embodiments may include removabletip 508 (such as previously described). Of course, unit 500 may containelements of the various embodiments as previously described herein.

[0218] Charging stand 526 preferably includes socket/holder 532 forholding unit 500 while it is being recharged, and preferably includes asocket to connect to wired serial port 518, wireless IR serialtransceiver 530, wired serial port 524 (such as an RS232 port) forconnection to a host computer (such as previously described), powercable 522 for providing external power to the system, and lamps 528showing the charging state of the battery and/or other statusinformation or the like.

[0219] The system battery may be charged in charging stand 526 in aconventional manner. A charging indicator (such as lamps 528) may beused to provide an indication of the state of the internal battery. Unit500 may be removed from the stand, and an optical measurement may bemade by the dentist. If the dentist chooses, the optical measurement maybe read from display 502, and a prescription may be handwritten orotherwise prepared by the dentist. Alternately, the color/opticalcharacteristics data may be transmitted by wireless IR transceiver 514(or other cordless system such as RF) to a wireless transceiver, such astransceiver 530 of charging stand 526. The prescription may then beelectronically created based upon the color/optical characteristicsdata. The electronic prescription may be sent from serial port 524 to acomputer or modem or other communications channel to the dentallaboratory.

[0220] With reference to FIGS. 37A and 37B, additional aspects of thepresent invention will be discussed.

[0221] As is known, human teeth consist of an inner, generally opaque,dentin layer, and an outer, generally translucent, enamel layer. Aspreviously discussed, light that is incident on a tooth generally can beaffected by the tooth in three ways. First, the light can be reflectedfrom the outer surface of the tooth, either diffusely or specularly.Second, the light can be internally scattered and absorbed by the toothstructures. Third, the light can be internally scattered and transmittedthrough the tooth structures and re-emerge from the surface of thetooth. Traditionally, it was difficult, if not impossible, todistinguish light reflected from the surface of the tooth, whetherspecularly or diffusely, from light that has penetrated the tooth, beenscattered internally and re-emitted from the tooth. In accordance withthe present invention, however, a differentiation may be made betweenlight that is reflected from the surface of the tooth and light that isinternally scattered and re-emitted from the tooth.

[0222] As previously described, a critical height h_(c) occurs when apair of fiber optics serve to illuminate a surface or object and receivelight reflected from the surface or object. When the probe's distancefrom the tooth's surface is greater than the critical height h_(c) thereceiver fiber optic is receiving light that is both reflected from thetooth's surface and light that is internally scattered and re-emitted bythe tooth. When the distance of the probe is less than the criticalheight h_(c), light that is reflected from the surface of the tooth nolonger can be received by the received fiber optic. In general, the onlylight that can be accepted by the receiver fiber optic is light that haspenetrated enamel layer 540 and is re-emitted by the tooth (in caseswhere the object is a tooth).

[0223] Most of the internal light reflection and absorption within atooth occurs at enamel-dentin interface or junction (DEJ) 542, which ingeneral separates enamel layer 540 from dentin 544. In accordance withthe present invention, an apparatus and method may be provided forquantifying optical properties of such sub-surface structures, such asthe color of DEJ 542, with or without comparison with data previouslytaken in order to facilitate the assessment or prediction of suchstructures.

[0224] Critical height h_(c) of the fiber optic probe such as previouslydescribed is a function of the fiber's numerical aperture and theseparation between the fibers. Thus, the critical height h_(c) of theprobe can be optimized based on the particular application. In addition,a probe may be constructed with multiple rings of receive fiber opticsand/or with multiple numerical aperture receiving fiber optics, therebyfacilitating assessment, etc., of enamel thickness, surface gloss, toothmorphology etc.

[0225] It is widely known that the thickness of the enamel layer of atooth varies from the incisal edge to the cervical portion of the toothcrown, and from the middle of the tooth to the mesial and distal edgesof the tooth (see FIGS. 37A and 37B, etc.). By utilizing multiple ringsof receiver fiber optics, a measurement of the approximate thickness ofthe enamel layer may be made based on a comparison of the peak intensityabove the tooth surface and a measurement in contact with the toothsurface. A probe with multiple critical heights will give differentintensity levels when in contact with the tooth surface, therebyproducing data that may be indicative of the degree of internalscattering and enamel thickness or tooth morphology at the point ofcontact, etc.

[0226] Accordingly, in accordance with the present invention, the coloror other optical characteristics of a sub-surface structure, such as DEJ542 of a tooth, may be assessed or quantified in a manner that is ingeneral independent of the optical characteristics of the surface of thetooth, and do so non-invasively, and do so in a manner that may alsoassess the thickness of the outer layer, such as enamel layer 540.

[0227] Additionally, and to emphasize the wide utility and variabilityof various of the inventive concepts and techniques disclosed herein, itshould be apparent to those skilled in the art in view of thedisclosures herein that the apparatus and methodology may be utilized tomeasure the optical properties of objects/teeth using other opticalfocusing and gathering elements, in addition to the fiber opticsemployed in preferred embodiments herein. For example, lenses or mirrorsor other optical elements may also be utilized to construct both thelight source element and the light receiver element. A flashlight orother commonly available light source, as particular examples, may beutilized as the light source element, and a common telescope with aphotoreceiver may be utilized as the receiver element in a large scaleembodiment of the invention. Such refinements utilizing teachingsprovided herein are expressly within the scope of the present invention.

[0228] As will be apparent to those skilled in the art, certainrefinements may be made in accordance with the present invention. Forexample, a central light source fiber optic is utilized in certainpreferred embodiments, but other light source arrangements (such as aplurality of light source fibers, etc.). In addition, lookup tables areutilized for various aspects of the present invention, but polynomialtype calculations could similarly be employed. Thus, although variouspreferred embodiments of the present invention have been disclosed forillustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and/or substitutions are possiblewithout departing from the scope and spirit of the present invention asdisclosed in the claims. In addition, while various embodiments utilizelight principally in the visible light spectrum, the present inventionis not necessarily limited to all or part of such visible lightspectrum, and may include radiant energy not within such visible lightspectrum.

[0229] In addition to the foregoing embodiments, features, applicationsand uses, other embodiments and refinements in accordance with thepresent invention will now be described. As with prior descriptions,descriptions to follow are without being bound by any particular theory,with the description provided for illustrative purposes. As before,although certain of the description to follow makes reference to objectsor materials, within the scope of the various embodiments of the presentinvention are dental objects such as teeth. Also as before, teeth or anyother particular objects referenced herein are exemplary uses, andvarious embodiments and aspects of the present invention may be used inother fields of endeavor.

[0230] A variety of devices may be used to measure and quantify theintensity of light, including, for example, photodiodes, charge coupleddevices, silicon photo detectors, photomultiplier tubes and the like. Incertain applications it is desirable to measure light intensity over abroad band of light frequencies such as over the entire visible band. Inother applications it is desirable to measure light intensities overnarrow bands such as in spectroscopy applications. In yet otherapplications it is desirable to measure high light intensities such asin photographic light meters. In still other applications it isdesirable to measure low light intensities such as in abridgedspectrometers. Typically when measuring low light intensities, longsampling periods of the order of one second or longer are required.

[0231] In accordance with other aspects of the present invention, amethod and apparatus are disclosed that may be used to measure multiplelight inputs rapidly. Such an embodiment preferably utilizes aphotodiode array, such as the TSL230 manufactured by Texas Instruments,Inc., and a gate array manufactured by Altera Corporation or Xilinx,Inc. In certain applications, such an embodiment may be utilized tomeasure broad band visible and infrared light. In other applications,such an embodiment may be utilized as an abridged spectrometer in whicheach photodiode array has a notch filter, such as an interferencefilter, positioned above the light sensor.

[0232] The TSL230 consists of 100 silicon photodiodes arranged in asquare 10 by 10 array. The 100 photodiodes serve as an input to anintegrator that produces an output signal of a frequency proportional tothe intensity of light incident upon the array. The TSL230 has scale andsensitivity inputs allowing the sensitivity and scale to each be variedby a factor of 100, for a net range of 10⁴. The output frequency canvary from a maximum of approximately 300 k Hz (sensor is saturated) tosub Hz ranges. Thus, the sensor can detect light inputs ranging overseven orders of magnitude by varying the sensitivity and/or scale of thesensor and can detect light ranges of over five orders of magnitude at agiven setting.

[0233] In spectroscopy applications for such embodiments, each sensor ismounted with an optical filter such as an interference filter. As isknown in the art, interference filters have high out-of-band rejectionand high in-band transmission, and may be constructed with very narrowband pass properties. As an example, interference filters may beconstructed with band pass ranges of 20 nanometers or less. Inaccordance with certain aspects of the present invention, anabridged-type spectrometer may be constructed with TSL230 (or similar)sensors and interference filters that is suitable for reflectivity ortransmission spectrographic applications such as measuring the color ofobjects. In color determination applications it is not necessary todetect “line” spectra, but it often is desirable to have high gray scaleresolution, e.g., to be able to resolve the light intensity to 1 part in1000 or greater.

[0234] Instruments and methods for measuring the optical properties ofmaterials and objects have been previously described. Such an instrumentmay consist of a probe and an abridged spectrometer. The probe may bemoved into contact or near contact with the surface of the material orobject (by movement of the probe or material/object, etc.), and thespectrum of the light received by the probe was analyzed as the probewas moved towards the surface. Since the probe was not stationary,preferably numerous measurements are taken in succession, with thespectra dynamically taken and/or analyzed as the probe relatively movesin proximity with the object.

[0235] One difficulty that results from narrowing the band width ofnotch or interference filters is that such narrowing reduces the lightintensity incident upon each sensor. Thus, to measure low light levels,long sampling times typically are required. In the case of the TSL230sensor, as the light level decreases, the output frequency of the devicedecreases. Thus, if it is desired to make 200 samples per second with anabridged spectrometer constructed with notch filters and TSL230s, oneneeds enough light to cause the TSL230 output to oscillate at a rate ofat least 200 Hz. Since the maximum range of the sensor is approximately300 k Hz, the maximum dynamic range of the sensor is reduced to (300 kHz)/(200 Hz) or roughly 1.5×10³. If the light inputs are low, then thedynamic range is reduced still further.

[0236]FIG. 38 illustrates an abridged visible light range spectrometerin accordance with another embodiment of the present invention. Thisembodiment utilizes TSL230 sensors 616, a light source or lamp 604,preferably a hot mirror that reflects IR light with wavelengths above700 nanometers (not expressly shown in FIG. 38), fiber optic cableassembly consisting of one or more sources (illustrated by light path608) providing light to object 606, and one or more receivers(illustrated by light path 618) receiving light from object 606, gatearray 602 such as an Altera FLEX 10K30 ™ (believed to be a trademark ofAltera Corporation), which is coupled to computer 600 and receivessignal inputs from sensors 616 over bus 620. In one preferred embodimentup to fifteen or more TSL230 sensors are utilized. Each TSL230 sensor616 has an interference filter 614 positioned above the sensor, witheach filter preferably having a nominal bandwidth of 20 nanometers (orother bandwidth suitable for the particular application). Sensors 616also preferably receive a small and controlled amount of light (lightpath 610) directly from light source 604, preferably after IR filtering.The light source input to sensors 616 serves to bias sensors 616 toproduce an output of at least 200 Hz when no light is input to sensors616 from filters 614. Thus, sensors 616 will always produce an outputsignal frequency greater than or equal to the sampling frequency of thesystem. When input light intensities are small, the frequency change issmall, and when the light input is large, the frequency change will belarge. The scale and sensitivity of sensors 616 are set (by gate array602 over control bus 612, which may be under control of computer 600) todetect the entire range of light input values. In most cases,particularly in object color determination, the maximum amount of lightinput into any one of sensors 616 is determined by light source 604 andfilters 614 and can be appropriately controlled.

[0237] Gate array 602 serves to measure the output frequency and periodof each of sensors 616 independently. This may be done by detectingwhenever an output changes and both counting the number of changes persampling period and storing the value of a high speed counter in a firstregister the first time an output changes, and storing the value in asecond register for each subsequent change. The second register willthus hold the final value of the timer. Both high to low and low to hightransitions preferably are detected. The output frequency (f) of eachsensor is thus: $\begin{matrix}{f = \frac{\left( {N - 1} \right)}{\left( {P_{h} - P_{l}} \right)}} & \left. 1 \right)\end{matrix}$

[0238] where:

[0239] N=Number of transitions in sample period;

[0240] P_(l)=Initial timer count; and

[0241] P_(h)=Final timer count.

[0242] The internal high speed-timer is reset at the start of eachsampling period ensuring that the condition P_(h)>P_(l) is always true.

[0243] The precision of a system in accordance with such an embodimentmay be determined by the system timer clock frequency. If P_(r) is thedesired precision and S_(r) is the sampling rate, then the frequency ofthe timer clock is:

f _(t) =P _(r) ·S _(r)  2)

[0244] For example, for a sampling rate of 200 and a precision of 2¹⁶,the timer clock frequency is 200×2¹⁶ or 13 MHz.

[0245] If the input light intensities are high, N will be a largenumber. If the input light intensities are low, N will be small (butalways greater than 2, with proper light biasing). In either case,however, P_(h)−P_(l) will be a large number and will always be on theorder of ½ the precision of the system. Thus, in accordance with suchembodiments, the theoretical precision to which, the light intensitiescan be measured may be the same for all sensors, independent of lightinput intensity. If one sensor has an output range of 200 to 205 Hz(very low light input), the intensities of light received by this sensormay be measured to about the same precision as a sensor with 10,000times more light input (range of 200 to 50,200 Hz). This aspect of suchembodiments is very unlike certain conventional light sensors, such asthose utilizing ADCs, analog multiplexers and sample and holdamplifiers, where the precision of the system is limited to the numberof bits of the ADC available over the input range. To provide for thewide input range in a system with an ADC, a variable gain sample andhold amplifier typically is required. It is also difficult for an ADC tosample to 16 bits accurately.

[0246] With such embodiments of the present invention, the absoluteaccuracy generally is limited by the stability of the lamp andelectrical noise, both of which may be reduced and in general areminimal because of the simplicity of the design and the few componentsrequired on a circuit card. A gate array, which may be fieldprogrammable or the like, typically may readily accommodate 20 or moreTSL230 sensors and also provide for an interface to a computer,microprocessor or microcontroller utilizing the light data. It alsoshould be noted that, instead of a gate array, such embodiments may beimplemented with high speed RISC processors or by DSPs or otherprocessing elements.

[0247] It should be noted that the use of light biasing, and otheraspects thereof, also are described elsewhere herein.

[0248] In addition to the foregoing embodiments, features, applicationsand uses, still other embodiments and refinements in accordance with thepresent invention will now be described.

[0249] Certain objects and materials such as gems and teeth exhibitreflected light spectrums that are a function of incident light angleand reflected light angle. Such objects and materials are sometimesreferred to as opalescent materials. In accordance with otherembodiments of the present invention, instruments and methodologies maybe provided for specifically measuring and/or quantifying the opalescentcharacteristics of objects and materials, in addition to characteristicssuch as color, gloss, translucency and surface texture, it beingunderstood that previously described embodiments also may be used tocapture spectral and other data (such as a plurality of spectrums),which can be compared and/or processed to quantify such opalescentmaterials.

[0250] Such a further embodiment of the present invention is illustratedin FIG. 39. In accordance with this embodiment, light source 638provides light coupled through a light path (preferably light sourcefiber 636) to probe 630 through optical cable 632. Light received by theprobe (i.e., returned from the object or material being evaluated) iscoupled to spectrometer/light sensors 640 through a suitable light path(preferably one or more light receiver fibers from optical cable 632).Computer 642 is coupled to spectrometer/light sensors 640 by way ofcontrol/data bus 648. Computer 642 also is coupled to light source 638by way of control line(s) 646, which preferably control the on/offcondition of light source 638, and optionally may provide other controlinformation, analog or digital signal levels, etc., to light source 638as may be desired to optimally control the particular light chosen forlight source 638, and its particular characteristics, and for theparticular application. Light from light source 638 optionally may becoupled to spectrometer/light sensors 640 by light path 644, such as forpurposes of providing light bias (if required or desired for theparticular spectrometer chosen), or for monitoring the characteristicsof light source 638 (such as drift, temperature effects and the like).

[0251] Computer 642 may be a conventional computer such as a PC ormicrocontroller or other processing device, and preferably is coupled toa user interface (e.g., display, control switches, keyboard, etc.),which is generically illustrated in FIG. 39 by interface 652.Optionally, computer 642 is coupled to other computing devices, such asmay be used for data processing, manipulation, storage or furtherdisplay, through interface 650. Computer 642 preferably includes thetypical components such as (but not limited to) a CPU, random access orother memory, non-volatile memory/storage for storing program code, andmay include interfaces for the user such as display, audio generators,keyboard or keypad or, touch screen or mouse or other user input device(which may be through interface 652), and optionally interfaces to othercomputers such as parallel or serial interfaces (which may be throughinterface 650). Computer 642 interfaces to spectrometer/light sensors640 for control of the spectrometer and overall system and to receivelight intensity and light spectrum data from spectrometer/light sensors640. In a preferred embodiment, control/data bus 648 for interfacing tospectrometer/light sensors 640 is a standard 25 pin bi-directionalparallel port. In certain embodiments, computer 642 may be separate,standalone and/or detachable from spectrometer/light sensors 640 and maybe a conventional laptop, notebook or other portable or handheld-typepersonal computer. In other embodiments, computer 642 may be an integralpart of the system contained in one or more enclosure(s), and may be anembedded personal computer or other type of integrated computer.Purposes of computer 642 preferably include controlling light source 638and spectrometer/light sensors 640, receiving light intensity andspectral or other data output from spectrometer/light sensors 640,analyzing received or other data and determining the optical propertiesof the object or material, and displaying or outputting data to a useror other computing device or data gathering system.

[0252] In a preferred embodiment, the output end of probe 630 may beconstructed as illustrated in FIG. 40. Numerous other probeconfigurations, including probe configurations as described elsewhereherein, may be used in such embodiments. In accordance with suchpreferred embodiments, optical characteristics determinationsystems/methods may be obtained that provide for a broader range ofmeasurement parameters, and, in certain applications, may be easier toconstruct. Probe cross section 656 includes central fiber optic 658,which is preferably surrounded by six perimeter fiber optics 660 and662. Central fiber optic 658 is supplied by light from the light source(such as light source 638). Six perimeter fiber optics 660 and 662 arelight-receivers and pass to spectrometer/light sensors 640. In onepreferred embodiment, all seven fiber optics have the same numericalaperture (NA); however, as disclosed below, the numerical aperture ofthe light source and consequently the source fiber optic preferably canbe varied. Also, in certain embodiments the received cone of light fromcertain of the receiver fiber optics is also controlled and varied toeffectively vary the NA of certain receivers.

[0253] As illustrated in FIG. 40, central fiber optic 658 (S) serves asthe light source. Fiber optics 660 labeled 1,3,5 preferably are “wideband” fibers and pass to light sensors (preferably withinspectrometer/light sensors 640) that measure light intensity over anentire spectral range. The other three light receivers 662 labeled 2,4,6preferably are “dual” receivers and pass to both a spectrometer and to“wide band” light sensors (also preferably within spectrometer/lightsensors 640). As previously described, the probe in conjunction with aspectrometer, computer, light source and “wide band” light receivers canbe used to measure the color and translucency and surface properties ofteeth and other materials. Also as previously described, the probe witha combination of NA “wide band” receiver fiber optics can additionallybe utilized to measure the gloss or the degree of specular versusdiffuse light received from a surface.

[0254]FIG. 41A is a diagram of a preferred embodiment ofspectrometer/light sensors 640. In this embodiment, certain opticalfibers from the probe are coupled to wide band light sensors (suchsensors, which may include TSL230 sensors and optics and/or filters asdescribed elsewhere herein are illustrated as sensors 676 in FIG. 41A),while other of the optical fibers are coupled to both a spectrometer, inorder to spectrally measure the light received by the probe, and to wideband light sensors. Fibers 660 (1,3,5) preferably are coupled to threewide band light sensors (light path 682 of FIG. 41A). Preferably, thelight receiving/sensing elements are Texas Instruments TSL230s, althoughthey may also be photo diodes, CCDs or other light sensors. Fibers 660(1,3,5) preferably are masked by iris 694 to reduce the size of the coneof light produced by the fiber as illustrated in FIG. 42. Mask or iris694 serves to limit the NA of the receiver by allowing only light rayswith a maximum angle of a to be received by the receiver light sensor.

[0255] If:

[0256] h=height of end of fiber to iris

[0257] r=radius of opening of the iris

[0258] a=radius of the fiber

[0259] 1) then: $\alpha = {{Tan}^{- 1}\left( \frac{r + a}{h} \right)}$

[0260] Hence, the effective NA of the receiver fiber optic can bereduced and controlled with iris 694. By utilizing a variable iris or aniris that is controlled with a servo such as those utilized inconventional cameras, the NA of the receiver fiber optic can becontrolled by the system and can be varied to best match the object ormaterial being measured. Referring again to FIG. 42, exemplary receiverfiber 690 provides light to exemplary light sensor 676 through iris 694.Light rays such as light rays 696A of a certain limited angle passthrough iris 694, while other light rays within the acceptance angle offiber 690 (the outer limit of the acceptance angle is illustrated bydashed line 696 in FIG. 42) but not within the limited angular rangeallowed by iris 694 are blocked, thereby enabling iris 694 toeffectively emulate having a reduced or variable NA light receiver.

[0261] Referring again to FIG. 41A, light source 638 may be coupled tocertain of sensors 676 through light path 674. Light bias, such aspreviously described, may be provided from the light source, oralternatively, from separately provided LED 680, which may couple lightto certain of sensors 676 for providing controllable light bias tosensors 676 through light conduit 678. Control of LED 680 for providingcontrollable light bias to certain of sensors 676, etc., is describedelsewhere herein. Light from fibers 662 preferably are coupled (throughlight path 684 in FIG. 41A) to one or more diffusing cavities 686(described in more detail elsewhere herein), outputs of which arecoupled to certain of sensors 676 through light paths/conduits 688 asillustrated. Control of sensors 676, and data output from sensors 676,preferably is achieved by way of gate array 670, which may be coupled toa computing device by way of interface 668 (the use of gate array orsimilar processing element and the use of such a computer device aredescribed elsewhere herein).

[0262] The use of diffusing cavities 686 in such embodiments will now befurther described. As illustrated, certain of the light receivers 662(2,4,6) may be coupled to one or more diffusing cavities 686 throughlight path 684, which may serve to split the light receivers into, forexample, six (or more or fewer) fiber optics with a diffusing cavity asillustrated in FIGS. 43A, 43B, and 43C. One of light receivers 662 isthe central fiber in diffusing cavity 686 and is surrounded by six fiberoptics 702 as part of fiber optic bundle 698. Diffusing cavity 686serves to remove any radial or angular light distribution patterns thatmay be present in receiver fiber optic 662, and also serves to moreevenly illuminate the six surrounding fiber optics. Thus, lightreceivers 662 (2,4,6) illustrated in FIG. 40 may each be split into six(or a different number) fibers resulting in eighteen receivers. Three ofthe eighteen fibers, one per diffusing cavity, preferably pass to wideband sensors which may have iris 694 (see FIG. 42). The other fifteenfibers preferably pass to a spectrometer system (such as part ofspectrometer/light sensors 640, which may consist of a plurality ofsensors 676, such as previously described). For the visible band,fifteen fiber optics and interference notch filters preferably are usedto provide a spectral resolution of: $\begin{matrix}{\frac{{700\quad {nm}} - {400\quad {nm}}}{15} = {20\quad {{nm}.}}} & \left. 2 \right)\end{matrix}$

[0263] A greater or lesser number of fibers and filters may be utilizedin accordance with such embodiments in order to increase or decrease thespectral resolution of the system/spectrometer.

[0264] In FIGS. 41B and 43C, an alternate embodiment of the presentinvention utilizing a different arrangement of diffusing cavity 686 willnow be described. In such embodiments, three “dual band” receivers 662are all positioned in common fiber optic bundle 698 and one diffusingcavity 686 is utilized. Fiber optic bundle 698 preferably contains threereceiver fibers 662 and fifteen additional fibers 703 for thespectrometer system, although greater or fewer fibers may be utilized inother arrangements depending on the number of color sensors in thesystem. In certain embodiments, fifteen fiber optics 703 in the bundlemay be of different diameters to increase the efficiency of diffusingcavity 686 and the cross sectional packing arrangement of the opticalfibers in fiber optic bundle 698. As an example of such preferred fiberbundle arrangements in accordance with such embodiments, larger diameterfibers may be utilized for the color filters in the blue range of thevisible spectrum, where the light intensity from a tungsten-halogen lampsource 638 is significantly less than in the red region of the visiblespectrum.

[0265] As described elsewhere herein, a spectrometer system may beconstructed of Texas Instruments TSL230 light sensors, interferencefilters, light biasing elements and a gate array such an Altera FLEX10K30 in order to control the light sensors, interface to a computer viaa parallel or other interface and to measure the frequency and period ofthe light sensors simultaneously at a high rate in order to accuratelyand rapidly measure light spectrums and light intensities. Although suchspectrometer systems are used in preferred embodiments, otherspectrometers such as those utilizing, for example, CCDs withdiffraction gratings are utilized in other embodiments.

[0266]FIG. 44 illustrates a further refinement of aspects of aspectrometer-type system in accordance with the present invention. Afiber optic, such as one of the fifteen fibers from three diffusingcavities as described earlier, preferably pass to light sensor 710(which may be a TSL230 light sensor, as previously described) throughinterference filter 708. Interference filters such as interferencefilter 708 serve as notch filters passing light over a narrow bandwidthand rejecting light that is out of band. The bandwidth of the lighttransmitted through the filter, however, is dependent upon the angle ofincidence of the light on the filter, and in general is broadened as theangle of incidence increases. Since fiber optics produce a cone oflight, it has been determined that it is desirable to collimate the coneto reduce such bandwidth spreading. As illustrated in FIG. 44, the coneof light produced by exemplary fiber optic 704 (illustrated by lines712A) preferably is collimated with first aspheric lens (or fresnellens) 706A (illustrated by lines 712B) prior to entering interferencefilter 708. Light emitted from filter 708 (illustrated by lines 712C) is“gathered” by second aspheric lens (or fresnel lens) 706B to concentrate(illustrated by lines 712D) as much light as possible on light sensor710. In accordance with such embodiments, filters, particularlyinterference-type filters, may more optimally be utilized in a manner toreduce such bandwidth spreading or other undesirable effects.

[0267] Referring again to FIG. 41A (the discussion also is generallyapplicable to FIG. 41B), light biasing as previously described will bediscussed in greater detail. As previously described, in order torapidly sample TSL230-type sensors, the sensors may require lightbiasing. Without light biasing, depending upon the light intensitypresented to the particular sensors, a TSL230 sensor may not produce anoutput change pair of transitions (e.g., high to low and low to hightransitions, or low to high and high to low transitions) during thesampling period, hence a light intensity measurement may not be possiblefor that sensor. In preferred embodiments, the sensing system detectsboth high to low and low to high transitions and requires at minimum twotransitions to make a measurement. In other words, such system measureshalf periods. For example, assume that as the light intensity on aparticular TSL230 decreases such that its output frequency decreasesfrom 201 Hz to 199 Hz. At 201 Hz, the output of the TSL230 transitionswith a period of {fraction (1/201)} sec or every 4.975 ms. At 199 Hz,the output transition period is {fraction (1/199)} sec or 5.025 ms. Ifthe sampling rate is 200 samples per second, then the sampling period is5.00 ms. Thus, if the TSL230 transitions every 4.975 ms, the sensingsystem will always detect either two or three transitions and willalways be able to make an intensity measurement. At 199 Hz, however, thedetection circuitry will detect either one or two transitions. As aresult, during certain sampling intervals, measurements are possible,while during other intervals measurements are not possible, therebyresulting in measurement discontinuities even though the light intensityhas not changed.

[0268] It is desirable to measure light over a broad range of intensityvalues at high rates including very lowlight intensities. By utilizinglight biasing of the TSL230 sensors as illustrated in FIG. 41A, theminimal output frequency of the TSL230s can be controlled. The minimallight value preferably is measured as part of a normalization orcalibration procedure as follows.

[0269] 1. The light bias is turned on and allowed to stabilize.

[0270] 2. The probe is placed into a black enclosure. A “black level”intensity measurement I_(b) is made and recorded for each sensor,preferably in a simultaneous manner.

[0271] 3. The light source is turned on and allowed to stabilize. A“white level” intensity measurement I_(w) is made and recorded for eachsensor, again preferably in a simultaneous manner, on a “white” standardsuch as barium sulfide or on “Spectralon,” believed to be a trademarkedproduct of Labsphere, Inc. The actual intensities measured by allsensors will vary from the standard values I_(s). Typically in colormeasurements the standard value I_(s) is nominally “100%.”

[0272] 4. Subsequent light measurements may be normalized by subtractingthe “black level” intensity and by adjusting the gain from the whitelevel measurement resulting in a normalized intensity I_(N) for eachsensor as follows: $\begin{matrix}{I_{N} = {\frac{I_{s}}{I_{w} - I_{b}}\left( {I - I_{b}} \right)}} & \left. 3 \right)\end{matrix}$

[0273] where I=Intensity measurement and I_(N) is the normalized orcalibrated intensity measurement. It should be noted that in suchpreferred embodiments the normalization is made for each light sensor,and independent “black level” and “white level” intensities are savedfor each sensor.

[0274] In certain situations, a long time may be required for the lightsource and for the light bias source to stabilize. In other situations,the light source and bias source may drift. In preferred embodiments,the light source is a 18W, 3300K halogen stabilized tungsten filamentlamp manufactured by Welch Allyn, Inc. The light bias preferably isprovided by a high intensity LED and a fiber optic light guide orconduit (see LED 680 and light conduit 678 of FIG. 41A) that passes toeach biased sensor of sensors 676. The intensity of LED 680 preferablyis controlled and varied with high frequency pulse width modulation, orby analog constant current controllers. By controlling the intensity ofbias LED 680, the bias light level can be varied to best match thesensor sampling rate.

[0275] Preferably, one sensor, such as a TSL230 sensor, is provided tomeasure the intensity of LED 680 and to correct for intensity variationsof the LED light biasing system. Since LED 680 is monochromatic, onesensor typically is sufficient to track and correct for bias LEDintensity drift. The LED bias intensity preferably is measured andrecorded when the “black level” measurement is made. For each subsequentlight intensity measurement, the black level for each sensor iscorrected for LED drift as follows: $\begin{matrix}{{I_{b}({Corrected})} = {I_{b}\frac{I({BiasSensor})}{I_{b}({BiasSensor})}}} & \left. 4 \right)\end{matrix}$

[0276] where: I(BiasSensor) is the intensity measured by the biassensor, I_(b)(BiasSensor) is the “black level” intensity measured by thebias sensor, I_(b) is the “black level” intensity measured by a lightsensor (other than the bias sensor) and I_(b)(Corrected) is the adjustedbias used in equation 4) above.

[0277] Light source drift preferably is measured by a plurality of lightsensors. Since the light source is polychromatic light, its spectrum mayalso drift. It is understood that tungsten filament lamps producespectrums that are very nearly approximated by the spectrums of blackbody radiators and can be represented by the Planck law for black bodyradiators. $\begin{matrix}{{I(\lambda)} = {\left( \frac{2 \cdot \pi \cdot h \cdot c}{\lambda^{3}} \right)\left( \frac{1}{^{\frac{h \cdot c}{k \cdot T \cdot \lambda}} - 1} \right)}} & \left. 5 \right)\end{matrix}$

[0278] The only variable affecting the intensity of a black bodyradiator at any wavelength within the visible band is the temperature(T) of the source. Thus, a single narrow band light sensor may beutilized to detect temperature variations of such a source. Additionalfactors, however, may affect the spectral output of the lamp, such asdepositing of the filament on the lamp envelope or adjusting thespectrum of the lap as described below. In the preferred embodiment, formore accurate spectral corrections and intensity variations of the lamp,additional narrow band filters are utilized. In certain of suchpreferred embodiments, three band pass filters and sensors are utilizedto measure the spectral shift and intensity of the lamp in a continuousmanner, and such filters and sensors preferrably are further utilized tocorrect for lamp spectral and intensity drift.

[0279]FIG. 45 illustrates a preferred embodiment of a light source usedin preferred embodiments of the present invention. Such a light sourcepreferably consists of halogen tungsten filament lamp 724, with a lensmolded into the envelope of the lamp that produces a concentrated lightpattern on an axis parallel to the body of lamp 724. The use of such alens in lamp 724 is to concentrate the light output and to reduce theshadowing of the lamp filament that may result from lamps withreflectors. Hot mirror 722, which preferably is a “0° hot mirror,”reduces the intensity of IR light input into the system. In certainembodiments, the hot mirror may also contain color correctionproperties, for example, reducing light intensity for longer (red)wavelengths more than for shorter (blue) wavelengths. Light output fromlamp 724 passes through hot mirror 722 preferably to tapered glass rod720. The end of glass rod 720 nearest lamp 724 preferably has a diameternominally the diameter of the envelope of lamp 724. The other end ofglass rod 720 preferably is nominally 4 mm, or up to four times or morethe diameter of source fiber optic 714.

[0280] Glass rod 720 serves a number of purposes. First, glass rod 720serves as a heat shield for fiber optic 714 by allowing fiber optic 714to be displaced from lamp 724, with fiber optic 714 being thermallyinsulated from lamp 724 by the existence of glass rod 720. Second, glassrod 720 serves to concentrate the light over a smaller area near fiberoptic 714 and to broaden the angular distribution of light emerging fromthe narrow end to provide a distributed light pattern that can uniformly“fill” the NA of source fiber optic 714. Without tapered glass rod 720,the angular distribution pattern of light emerging from lamp 724 may notentirely or evenly fill the acceptance cone of source fiber optic 714.To ensure that source fiber optic 714 is desirably filled with lightwithout an implement such as glass rod 720 would require source fiberoptic 714 to be very close to lamp 724, thereby creating a risk thatsource fiber optic 714 will overheat and possibly melt.

[0281] Between source fiber optic 714 and glass rod 720 preferably isiris 718. Iris 718 preferably is utilized to limit the angular range oflight rays entering source fiber optic 714. When iris 718 is fully open,the entire acceptance cone of source fiber optic 714 may be filled. Asiris 718 is closed, the cone of light incident upon source fiber optic714 is reduced, and hence the angular distribution of light incidentupon fiber optic 714 is reduced. As iris 718 is reduced further, it ispossible to produce a nearly collimated beam of light incident uponfiber optic 714.

[0282] It is understood that a property of fiber optics whose ends arehighly polished perpendicular to the axis of the fiber optic is that theangle of light incident on one end of the fiber optic is preserved as itexits the other end of the fiber optic. As is known to those skilled inthe art, numerous technologies exist for polishing fiber optic cables.Thus, with a highly polished fiber optic, by varying the diameter ofiris 718, the cone of light entering source fiber optic 714 can becontrolled, and thus the cone of light emerging from source fiber optic714 can be controlled.

[0283] In an alternate embodiment, iris 718 is replaced by disk 730,which preferably includes a pattern of holes positioned near itsperimeter as illustrated in FIGS. 46A and 46B. Preferably, disk 730 isdriven with stepping motor 738 through gear 736 and gear teeth 730A sothat disk 730 may be rapidly moved to a desired position and held it ina stable position in order to make a light measurement. Stepping motor738 is controlled by a computer (such as described elsewhere herein;see, e.g., FIGS. 38 and 39), which controls disk 730 to rotate aboutaxis 732 and stop in a desired and controllable position. Thus, such acomputer in effect can vary the NA of the light source synchronously toeach measurement. The procedure preferably progresses as follows.

[0284] 1. Rotate the disk to the desired aperture.

[0285] 2. Pause to allow the disk to stabilize.

[0286] 3. Measure one light sample.

[0287] 4. Rotate the disk to the next desired aperture and repeat theprocess as required.

[0288] As illustrated FIG. 46B, the pattern of holes on disk 730 may beround or any other desired shape. Such apertures also may constitute apattern of microscopic holes distributed to affect the light pattern oflight or spectrum of light entering the source fiber. Additionally, thedisk may contain filters or diffraction gratings or the like to affectthe spectrum of the light entering the source fiber. Such holes orapertures also may consist of rings that produce cones of light wherethe light rays entering the fiber are distributed over a narrow or otherdesired range of angles. With the disk embodiment of FIGS. 46A and 46B,it is possible to control the light pattern of source fiber optic 714effectively over a wide range of angles.

[0289] Referring again to FIG. 45, light conduit 716 passes light suchas through light path 674 to sensors 676 (see, e.g., FIGS. 41A and 41B)for measuring the spectral properties of the lamp as described earlier.If the iris or aperture disk controlling the distribution of lightentering source fiber optic 714 modifies the spectral properties of thelight source, then the resulting spectrum can be adjusted as describedearlier.

[0290] When at pair of fiber optics is utilized as described hereinwhere one fiber serves as a light source and another fiber serves as alight receiver, the intensity of light received by the receiver fibervaries with the height of the pair above the surface of the object ormaterial and also with the angle of the pair relative to the surface ofthe object or material. As described earlier, in certain preferredembodiments the angle of the probe relative to the surface may bedetected by utilizing three or more fiber optic receivers having thesame receiver NA. After normalization of the system, if the intensitiesof the three receiver fibers (such as fibers 660 (1,3,5) in FIG. 40) arethe same, then this is an indication that the probe is perpendicular tothe surface. If the intensities vary between the three sensors, thenthis is an indication that the probe is not perpendicular to thesurface. As a general statement, this phenomenon occurs at all heights.In general, the intensity variation of the three fibers is dependentupon the geometry of the three fibers in the probe and is independent ofthe color of the material. Thus, as the probe is tilted towards fiber 1,for example, the intensities measured by sensors 3 and 5 will benominally equal, but the intensity measured by fiber 1 will vary fromfibers 3 and 5. As a result, the system can detect an angular shifttowards fiber 1. In preferred embodiments, by comparing the intensityvalues of fiber 1 to fibers 3 and 5, a measurement of the angle can bemade and the intensity of fibers 1, 3 and 5 can be corrected by acorrection or gain factor to “adjust” its light measurement tocompensate for the angular shift of the probe. It is thus possible withthe probe arrangement illustrated in FIG. 40 to detect and measureangular changes.

[0291] Angular changes also will affect the intensities measured by theother fibers 662 (2,4,6). In a similar manner, the difference betweenthe “wide band” sensors in fibers 662 (2,4,6) can also be utilized tofurther quantify the angle of the probe and can be utilized to adjustthe light intensity measurements. It should be noted, however, that theintensity shift due to angle of the probe affects the fibersdifferently. If sensors 662 (2,4,6) are utilized in the spectrometerillustrated in FIG. 41A, the intensity adjustment must be madeindependently for each fiber and for the set of six fibers emerging fromdiffusing cavity 686 illustrated in FIG. 43A. However, if one diffusingcavity 686 is utilized as illustrated in FIG. 41B, the angle correctionapplies to all sensors supplied by light paths 703 equally. With such anembodiment as illustrated in FIG. 41B, angle determination and/orcorrection may be made in a manner more desirable for some applications.

[0292] As the probe approaches the surface of an object or material (theprobe may be moved towards the material or the material may be movedtowards the probe), the source fiber illuminates the object/material.Some light may reflect from the surface of the object/material, and somelight may penetrate the object/material (if it is translucent or has atranslucent layer on its surface) and re-emerge from the material andmay strike the receiver fiber optic. As described elsewhere herein, theintensity measured by the receiver exhibits a peaking phenomenon wherethe light intensity varies to a maximum value, and then falls until theprobe is in contact with the object/material where it exhibits aminimum. If the object/material is opaque, then the light intensity atthe minimum is essentially zero. If the object/material is highlytranslucent, then the intensity may be near the peaking intensity.

[0293] Based on such phenomena, in accordance with other aspects of thepresent invention, it is possible to quantify the height of the probeand to adjust for height variations of the probe near the peaking heightby measuring the peaking height intensity of the “wide band” sensors andcomparing the intensity value at other heights and adjusting the gain ofall sensors by the ratio of the measured intensity to the peakingintensity. If I_(p) is the peak intensity of a wide band receiver, andI_(m) is the intensity measured when the probe is in contact with thematerial, and I is the intensity measured at a height less than thepeaking height then the ratio: $\begin{matrix}{G = \frac{I_{p} - I_{m}}{I - I_{m}}} & \left. 6 \right)\end{matrix}$

[0294] is the gain adjustment factor. If the gain adjustment factor isapplied to the spectrometer sensors, then the spectrum may be measuredindependent of height for a wide range of heights within the peakingheight.

[0295] Reference should now be made to FIGS. 47A and 47B. As a fiberoptic pair (e.g., source fiber, optic 742 and receiver fiber optic 744)approach a material or object 746, material or object 746 is illuminatedby source fiber optic 742 (see, e.g., lines 745 of FIG. 47A). The lightemitted from source fiber optic 742 may be controlled as describedelsewhere herein. Thus, source fiber optic 742 can be controlled so asto illuminate material or object 746 with nearly collimated light (smallincident angles), or source fiber optic 742 can be controlled toilluminate material or object 746 with wide incident angles, or with apattern of angles or with different spectral properties. If source fiberoptic 742 is illuminated with an aperture disk with a slit pattern asillustrated in FIG. 46B, then source fiber optic 742 may be used toilluminate material or object 746 with a narrow singular range ofangles.

[0296] Consider source fiber optic 742 and receiver fiber optic 744 withthe same NA as illustrated in FIGS. 47A and 47B. The angulardistribution of light provided by source fiber optic 742 is dependentupon the source fiber only (and the angle of the probe) and isindependent of the height of the fiber from the material. If the probeis held substantially perpendicular to material or object 746, theangular distribution of light is independent of height. The areailluminated by source fiber 742, however, is height dependent andincreases with increasing height. Receiver fiber optic 744 can onlyreceive light that is within its acceptance angle, thus it can onlydetect light reflected from the surface that is reflected from the areaof overlap of the two cones illustrated in FIGS. 47A and 47B.

[0297]FIG. 47A illustrates the fiber pair at the peaking height, whileFIG. 47B illustrates the fiber pair at the critical height. At thecritical height, the only light reflecting from the surface that can bereceived by receiver fiber 744 is the source ray 745 and the reflectedray 748 with angle of incidence equal to angle of reflection, or it canonly detect “spectrally” reflected light. When the probe is at thepeaking height, however, the reflected light rays that can be receivedby the receiver fiber vary over both a wider angle of incidence rangeand wider angle of reflection range. Thus, at the peaking height, thereceiver is detecting a broad range of incident angle light rays andreflected angle light rays. By adjusting the spectrum for height shiftsas described above and by detecting the angle of the probe relative tothe surface of the material or object, the reflected or returnedspectrum can be measured over a wide incident angular range andreflected angular range.

[0298] In general, for opaque surfaces, diffuse or specular, the heightadjusted spectrum will appear constant as the probe approaches thematerial or object. In general, for opalescent materials or objects,i.e., materials with a translucent surface in which light rays maypenetrate the material and be re-emitted, the height adjusted spectrumwill shift as the probe approaches the material or object. In general,for translucent materials such as teeth or gem stones, the spectrum willfurther shift when the probe is less than the critical height and incontact or near contact with the material or object.

[0299] As a further refinement to certain aspect of the presentinvention, the iris illustrated in FIG. 45 or the aperture diskillustrated in FIGS. 46A and 46B may be utilized. In one suchembodiment, the NA of source fiber optic 714 is held constant as theprobe approaches, the material or object, and light intensity andspectrum measurements are made and saved in a data queue as describedearlier. When the probe is in contact with the material or object, theNA of source fiber optic 714 is changed (either from narrow to wide orfrom wide to narrow, depending upon the state of the first set ofmeasurements), and spectral measurements are made as a function ofsource NA. The probe is then moved away from the material and lightintensity and spectral measurements are made as the distance from theprobe increases and as the probe passes through the peaking height. Thespectral shift that occurs as a result of the variance of the source NAand height preferably is used to quantify the opalescence of thematerial or object.

[0300] In an alternate embodiment, the aperture disk illustrated inFIGS. 46A and 46B is rotated by stepping motor 738 synchronously tomeasuring the light and spectral data as the probe is moved intoproximity to the material or object or into contact with the material orobject. In another alternate embodiment, the probe is positioned at afixed height from the material or in contact with the material or objectand the NA of the source fiber is varied as light intensity and spectraldata are measured. In yet another alternate embodiment, both the sourceand receiver fiber NAs are varied as described earlier, and theresulting spectra are utilized to quantify the optical properties of thematerial.

[0301] An alternative embodiment of the present invention forquantifying the degree of gloss of a material will now be described withreference to FIGS. 48A and 48B. FIGS. 48A and 48B illustrate source(742) and receiver (744) fiber pair positioned above a highly specularsurface such as a mirror (FIG. 48A) and above a diffuse surface (FIG.48B). The cone of light from source fiber optic 742 is illustrated bycircle 742A, and the acceptance cone of receiver fiber optic 744 isillustrated by circle 744A, with the overlap illustrated by area 750. Ona specular surface, the only light that will be received by receiverfiber optic 744 are the light rays whose angle of reflection equal theangle of incidence, thus the only light rays striking the surface ofreceiver 744 are the light rays striking, the small circular area thesize of the diameter of the fiber optics as illustrated by circle 752 inFIG. 48A. As long as receiver fiber optic 744 has an NA greater thansource fiber optic 742, all light incident upon receiver fiber optic 744will be accepted. Thus, the angular distribution of received light raysin receiver fiber optic 744 is limited to a very narrow range and isdependent upon the height of the fiber optic pair from the surface.

[0302] Consider FIG. 48B, which illustrates a fiber optic pairpositioned above a diffuse surface. Any light ray incident upon the areaof overlap of the two cones can be received by receiver fiber optic 744(provided of course that it is incident upon the receiver fiber). Thus,for diffuse surfaces, the angular distribution of light rays received byreceiver fiber optic 744 is also height dependent, but is greater thanthe angular distribution for a specular surface. In accordance with suchembodiments of the present invention, such angular distributionvariation may be used to quantify optical properties such as gloss for aparticular material or object.

[0303] A detector in accordance with other embodiments of the presentinvention is illustrated in FIG. 49, where single receiver fiber 758 ispositioned above a radial distribution of sensors (illustrated bysensors 760A and 760B). Two or more sensors may be utilized, in one ortwo dimensions, although only two sensors are illustrated in FIG. 49 fordiscussion purposes. In the illustrated embodiment, one sensor (sensor760B) is positioned corresponding to the center of fiber 758 andmeasures angles near zero, and the other sensor (sensor 760A) ispositioned at approximately ½ the acceptance angle of receiver fiber758. In alternate embodiments, the sensors may be arranged or configuredin a linear array such as a CCD, or a two dimensional sensor such as avideo camera CCD or MOS sensor. In accordance with aspects of thepresent invention, by analyzing the intensity patterns of the sensors,the degree of gloss of the material may be measured and quantified.

[0304] As the probe is moved towards the material object, the angulardistribution of light received by receiver fiber 758 changes dependentupon the surface of the material or object as illustrated in FIGS. 50Aand 50B. FIG. 50A illustrates the intensity pattern for the two sensorsor a specular surface, and FIG. 50B shows the intensity pattern for adiffuse surface. Specular materials in general will tend to exhibit apeaking pattern where the peaking intensity of sensor 1 is much largerthan the peaking intensity of sensor 2. For diffuse materials thepeaking intensity of sensor 2 (wide angles) is closer to the peakingintensity of sensor 1. By quantifying the variation in peaking intensitythe degree of gloss of the material can be additionally quantified. Inaddition, in alternative embodiments, the relative values of the sensorsat a time when one or the other sensors is peaking are captured andfurther used to quantify the optic properties of the material or object.

[0305] In conjunction with various of the foregoing embodiments, avariety of optic fibers may be utilized, with smaller fibers being usedto assess optical characteristics of smaller spots on the object ormaterial under evaluation. In accordance with such aspect of the presentinvention and with various of the embodiments described herein, fibersof about 300 microns in diameter, and up to or less than about 1millimeter in diameter, and from about 1 to 1.5 millimeters have beenutilized, although fibers of other diameters also are utilized in otherembodiments and applications of the present invention. With such fibers,the optical properties of the object or materials under evaluation maybe determined with a spot size of about 300 microns or alternativelyabout 1 millimeter, or about 1.5 millimeters, or from about 0.3 to 1millimeters, or from about 1 to 1.5 millimeters. In accordance with suchembodiments, optical properties of such a spot size, including spectral,translucence, opalescence, gloss, surface texture, fluorescence,Rayleigh scattering, etc., may be quantified or determined, including bydetermining a plurality of spectrums as the probe is directed towards orin contact or near contact with the object or material and possiblechanges in such spectrums, all with an instrument that is simplydirected towards a single surface of the object or material underevaluation.

[0306] It also should be noted that, in accordance with variousprinciples of the various embodiments of the present invention describedherein, refinements may be made within the scope of the presentinvention. Variations of source/receiver combinations may be utilized inaccordance with certain embodiments of the present invention, andvarious optical properties may be determined in accordance with thevarious spectra obtained with the present invention, which may includespectra taken at one or more distances from the object or material (andincluding spectrally reflected light), and spectra taken at or near thesurface (e.g., within the critical height, and substantially or whollyexcluding spectrally reflected light). In certain embodiments,measurements may be taken in a manner to produce what is sometimesconsidered a goniometric measurement or assessment of the object ormaterial under evaluation. In other embodiments, features may sometimesbe used with or without certain features. For example, certainapplications of aspects of the present invention may utilize perimeterfibers for height/angle determination or correction, while otherapplications may not. Such refinements, alternatives and specificexamples are within the scope of the various embodiments, of the presentinvention.

[0307] Reference is made to copending application filed on even dateherewith for Apparatus and Method for Measuring Optical Characteristicsof an Object, and for Method and Apparatus for Detecting and PreventingCounterfeiting, both by the inventors hereof, which are herebyincorporated by reference.

[0308] Additionally, it should be noted that the implements andmethodologies may be applied to a wide variety of objects and materials,illustrative examples of which are described elsewhere herein and/or inthe co-pending applications referenced above. Still additionally,embodiments and aspects of the present invention may be applied tocharacterizing gems or precious stones, minerals or other objects suchas diamonds, pearls, rubies, sapphires, emeralds, opals, amethyst,corals, and other precious materials. Such gems may be characterized byoptical properties (as described elsewhere herein) relating to thesurface and/or subsurface characteristics of the object or material. Asillustrative examples, such gems may be characterized as part of a buy,sell or other transaction involving the gem, or as part of a valuationassessment for such a transaction or for insurance purposes or the like,and such gems may be measured on subsequent occasions to indicatewhether gem has surface contamination or has changed in some respect orif the gem is the same as a previously measured gem, etc. Measuring agem or other object or material in accordance, with the presentinvention may be used to provide a unique “fingerprint” or set ofcharacteristics or identification for the gem, object or material,thereby enabling subsequent measurements to identify, or confirm theidentity or non-identity of, a subsequently measured gem, object ormaterial.

[0309] It also should be noted that the implements and methodologiesdescribed in the co-pending applications referenced above also may beapplied to embodiments and features of the present invention asdescribed herein. All such refinements, enhancements and further uses ofthe present invention are within the scope of the present invention.

What is claimed is:
 1. A method comprising the steps of: moving a probein proximity to a dental object, wherein the probe provides light to thesurface of the object from one or more light sources, and receives lightfrom the object through a plurality of light receivers, wherein theplurality of light receivers comprise one or more first light receiversand one or more second light receivers, wherein the one or more firstlight receivers have a first numerical aperture and the one or moresecond light receivers, have a second numerical aperture different fromthe first numerical aperture: determining the intensity of lightreceived by more than one of the light receivers; and measuring theoptical characteristics of the object, wherein the measurement producesdata indicative of the optical characteristics of the object.
 2. Themethod of claim 1, wherein the optical characteristics of the objectcomprise color characteristics.
 3. The method of claim 1, wherein theoptical characteristics of the object comprise translucencecharacteristics.
 4. The method of claim 1, wherein the opticalcharacteristics of the object comprise fluorescence characteristics. 5.The method of claim 1, wherein the optical characteristics of the objectcomprise surface texture characteristics.
 6. The method of claim 1,wherein the optical characteristics of the object comprise glosscharacteristics.
 7. A method comprising the steps of: moving a probetowards a surface of a dental object, wherein light is emitted by theprobe onto the object, and light is received from the object by theprobe; during the movement of the probe towards the surface of theobject, taking first measurements; when the probe is near the surface ofthe object, taking second measurements; based on the first and secondmeasurements, determining optical characteristics of the objectincluding one or more of the characteristics of the group consisting ofreflected surface color spectrum, bulk material color spectrum, gloss,translucency, fluorescence, and surface texture.
 8. The method of claim7, wherein the probe includes one or more light sources and at least twotypes of light receivers, wherein the first type of light receivers havea first numerical aperture and the second type of light receivers have asecond numerical aperture.
 9. The method of claim 7, further comprisingthe step of preparing a dental prosthesis based on the determinedoptical characteristics.
 10. The method of claim 7, further comprisingthe step of transmitting data indicative of the determined opticalcharacteristics to a remote location, and preparing a dental prosthesisbased on the determined optical characteristics at the remote location.11. The method of claim 7, further comprising the steps of: generatingfirst data corresponding to characteristics of the type of dental objectbeing measured; comparing the first data with the determined opticalcharacteristics; and assessing a condition of the object based on thecomparison.
 12. The method of claim 11, wherein the condition comprisesa condition relating to a subsurface feature of the object.
 13. Themethod of claim 7, wherein color spectrum data is adjusted based ondetermined gloss data.
 14. The method of claim 7, wherein color spectrumdata is adjusted based on determined translucency data.
 15. The methodof claim 7, wherein color spectrum data is adjusted based on determinedglossy and translucency data.
 16. A method comprising the steps of:moving a probe towards the surface of a dental object, wherein lightfrom one or more light sources is directed from the probe to the object;during the movement of the probe towards the surface of the object,taking first measurements; when the probe is near the surface of theobject, taking second measurements; based on the first and secondmeasurements, determining optical characteristics of the objectincluding one or more of the characteristics of the group consisting ofreflected surface color spectrum, bulk material color spectrum, gloss,translucency, fluorescence, and surface texture; and storing dataindicative of the determined optical characteristics in a data base. 17.The method of claim 16, further comprising the steps of: capturing animage of the object with an intra oral camera; and storing the capturedimage in the data base.
 18. The method of claim 17, further comprisingthe step of correlating the data indicative of the determined opticalcharacteristics with the captured image, wherein the captured imageincludes indicia of the location at which the optical characteristicswere determined.
 19. The method of claim 17, further comprising thesteps of: postureizing the object into at least first and secondregions; determining optical characteristics of the object in the firstand second regions; correlating data indicative of the determinedoptical characteristics in the first and second regions with thecaptured image, wherein the captured image includes indicia of the firstand second regions.
 20. The method of claim 19, further comprising thestep of preparing a dental prosthesis based on the determined opticalcharacteristics.
 21. The method of claim 19, further comprising the stepof transmitting data indicative of the determined opticalcharacteristics to a remote location, and preparing a dental prosthesisbased on the determined optical characteristics at the remote location.22. The method of claim 17, wherein the intra oral camera is positionedin the probe.
 23. The method of claim 17, wherein the light source andlight receivers comprise fiber optics.
 24. The method of claim 16,wherein the dental object comprises a tooth.
 25. The method of claim 16,wherein the probe is coupled to a dental chair adapted to hold the probeduring a time when the probe Is not taking measurements.
 26. The methodof claim 16, wherein the probe includes a removable tip.
 27. The methodof claim 16, wherein the probe is covered by a removable shield.
 28. Themethod of claim 27, wherein the shield is disposable.
 29. The method ofclaim 16, wherein data indicative of the determined opticalcharacteristics is coupled to a material preparation device, wherein thematerial preparation device prepares materials based on the determinedoptical characteristics.
 30. The method of claim 16, wherein thedetermined optical characteristics include a specular-included spectrumand a specular-excluded spectrum, wherein the specular-included spectrumsubstantially includes light specularly reflected from the object, andwherein the specular-excluded substantially excludes light specularlyreflected from the object.
 31. A method comprising the steps of: movinga probe towards a dental object, wherein light from one or more lightsources is emitted from the probe to the object; receiving light fromthe object with a plurality of light receivers on the probe, wherein thereceivers have numerical apertures and sizes sufficient to receive lightindicative of a specular-included spectrum and as specular-excludedspectrum, wherein the specular-included spectrum substantially includeslight specularly reflected from the object, and wherein thespecular-excluded substantially excludes light specularly reflected fromthe object.
 32. An apparatus for measuring optical characteristics of adental object with a probe as the probe is moved towards the surface ofthe object, comprising: a probe having one or more light sources and aplurality of light receivers, wherein the probe provides light to thesurface of the object from the one or more light sources, and receiveslight from the object through the plurality of light receivers, whereinthe plurality of light receivers comprise one or more first lightreceivers and one or more second light receivers, wherein the one ormore first light receivers have a first numerical aperture and the oneor more second light-receivers have a second numerical aperturedifferent from the first numerical aperture; sensors coupled to receivelight from the light receivers; a processor coupled to receive data fromthe sensors; wherein the processor makes a plurality of measurements anddetermines data indicative of the optical characteristics of the objectbased on the data received from the sensors.
 33. The apparatus of claim32, wherein the optical characteristics of the object comprise colorcharacteristics.
 34. The apparatus of claim 32, wherein the opticalcharacteristics of the object comprise translucence characteristics. 35.The apparatus of claim 32, wherein the optical characteristics of theobject comprise fluorescence characteristics.
 36. The apparatus of claim32, wherein the optical characteristics of the object comprise surfacetexture characteristics.
 37. The apparatus of claim 32, wherein theoptical characteristics of the object comprise gloss characteristics.38. The apparatus of claim 32, wherein the one or more light sources andplurality of light receivers comprise fiber optics.
 39. The apparatus ofclaim 32, wherein, during the movement of the probe towards the surfaceof the object, the processor takes first measurements, and when theprobe is near the surface of the object, the processor takes secondmeasurements; wherein, based on the first and second measurements, theprocessor determines data indicative of the optical characteristics ofthe object including one or more of the characteristics of the groupconsisting of reflected surface color spectrum bulk material colorspectrum, gloss, translucency, fluorescence, and surface texture. 40.The apparatus of claim 32, wherein the data indicative of the opticalcharacteristics of the object are coupled to a device for preparing adental prosthesis based on the determined optical characteristics. 41.The apparatus of claim 32, further means for transmitting dataindicative of the determined optical characteristics to a remotelocation, wherein a dental prosthesis based on the determined opticalcharacteristics is prepared at the remote location.
 42. The apparatus ofclaim 32, wherein the processor compares the determined opticalcharacteristics with first data corresponding to characteristics of thetype of object being measured, and the processor assesses a condition ofthe object based on the comparison.
 43. The apparatus of claim 42,wherein the condition comprises a condition relating to a subsurfacefeature of the object.
 44. The apparatus of claim 42, further comprisingan audio circuit for providing audio information, wherein the audioinformation provides information regarding the operation or status ofthe probe.
 45. The apparatus of claim 42, further comprising by audiocircuit for providing audio information the audio information providesinformation regarding the status of the optical characteristicsdetermination process.
 46. A method comprising the steps of: moving aprobe towards a dental object, wherein light from one or more lightsources is emitted from the probe to the object; receiving light fromthe object with a plurality of light receivers on the probe, wherein thereceivers have numerical apertures and sizes to receive light indicativeof a specular-included spectrum and a specular-only spectrum wherein thespecular included spectrum substantially includes light specularly anddiffusely reflected from the object, and wherein the specular-onlyspectrum substantially consists of light specularly reflected from theobject.
 47. A method of quantifying the color of a dental objectcomprising the steps of positioning a probe near the dental object,wherein light from one or more light sources is emitted from the probeto the object, and receiving light from the object with a plurality oflight receivers on the probe, wherein a reflected color spectrum of theobject is measured and translucency of the object is measured, whereinthe translucency measurement is used to adjust the color spectrummeasurement to compensate for translucency of the object.
 48. A methodof quantifying the color of a dental object comprising the steps ofpositioning a probe near the dental object, wherein light from one ormore light sources is emitted from the probe to the object, andreceiving light from the object with a plurality of light receivers onthe probe, wherein a reflected color spectrum of the object is measuredand gloss of the object is measured, wherein the gloss measurement isused to adjust the color spectrum measurement to compensate for gloss ofthe object.
 49. A method comprising the steps of: moving a probe towardsa dental object, wherein, lights from one or more light sources isemitted from, the probe to the dental object; receiving light from thedental object with one or more light receivers on the probe, wherein thereceivers receive light including light indicative of aspecular-excluded spectrum, wherein the specular excluded spectrumsubstantially excludes light specularly reflected from the dentalobject; and determining optical characteristics of the dental objectbased on the received light with a plurality of sensors.
 50. The methodof claim 49, wherein the sensors comprise a plurality of light receivingelements, wherein at least a plurality of the light receiving elementsreceive light through a filter, wherein the light receiving elements arecoupled to a gate array and a computing device.
 51. The method of claim49, wherein at least one of the sensors receives supplemental light,wherein the supplemental light provides light bias to the at least onesensor.
 52. The method of claim 51, wherein the light bias is providedby one of the one or more light sources.
 53. The method of claim 51,wherein the light bias is provided by a supplemental light source. 54.The method of claim 53, wherein the supplemental light source comprisesa light emitting diode.
 55. The method of claim 49, wherein one or moreof the sensors receive light through a aspheric lens.
 56. The method ofclaim 49, wherein one or more of the sensors receive light through afirst aspheric lens and a second aspheric lens.
 57. The method of claim56, wherein a filter is positioned between the first and second ashpericlens.
 58. The method of claim 57, wherein the filter comprises aninterference filter.
 59. The method of claim 49, wherein at least one ofthe one or more light sources provides light to the probe through aglass rod positioned between the at least one light source and one ormore optical fibers coupled to the probe.
 60. The met hod of claim 49,wherein at least one of the one or more light sources provides light tothe probe through an iris positioned between the at least one lightsource and one or more optical fibers coupled to the probe.
 61. Themethod of claim 60, wherein the iris comprises a movable disk having aplurality of apertures.
 62. The method of claim 49, wherein the sensorscomprise a spectrophotometer.
 63. A method comprising the steps of:moving a probe towards a dental object, wherein light from one or morelight sources is emitted from the probe to the dental object; receivinglight from the dental object with one or more light receivers on theprobe, wherein the receivers receive light indicative of aspecular-excluded spectrum, wherein the specular-excluded spectrumsubstantially excludes light specularly reflected from the dentalobject; taking a plurality of measurements based on the received light;and determining opalescence-type optical characteristics of the dentalobject based on the received light with a plurality of sensors.
 64. Themethod of claim 63, wherein the optical characteristics are determinedbased on a plurality of spectrums.
 65. The method of claim 64, whereinthe optical characteristics are determined based on changes between atleast first and second spectrums.